third_party/devtools/node_modules/acorn/CHANGELOG.md - cobalt - Git at Google

 ## 7.1.0 (2019-09-24)

 ### Bug fixes

 Disallow trailing object literal commas when ecmaVersion is less than 5.

 ### New features

 Add a static `acorn` property to the `Parser` class that contains the entire module interface, to allow plugins to access the instance of the library that they are acting on.

 ## 7.0.0 (2019-08-13)

 ### Breaking changes

 Changes the node format for dynamic imports to use the `ImportExpression` node type, as defined in [ESTree](https://github.com/estree/estree/blob/master/es2020.md#importexpression).

 Makes 10 (ES2019) the default value for the `ecmaVersion` option.

 ## 6.3.0 (2019-08-12)

 ### New features

 `sourceType: "module"` can now be used even when `ecmaVersion` is less than 6, to parse module-style code that otherwise conforms to an older standard.

 ## 6.2.1 (2019-07-21)

 ### Bug fixes

 Fix bug causing Acorn to treat some characters as identifier characters that shouldn't be treated as such.

 Fix issue where setting the `allowReserved` option to `"never"` allowed reserved words in some circumstances.

 ## 6.2.0 (2019-07-04)

 ### Bug fixes

 Improve valid assignment checking in `for`/`in` and `for`/`of` loops.

 Disallow binding `let` in patterns.

 ### New features

 Support bigint syntax with `ecmaVersion` >= 11.

 Support dynamic `import` syntax with `ecmaVersion` >= 11.

 Upgrade to Unicode version 12.

 ## 6.1.1 (2019-02-27)

 ### Bug fixes

 Fix bug that caused parsing default exports of with names to fail.

 ## 6.1.0 (2019-02-08)

 ### Bug fixes

 Fix scope checking when redefining a `var` as a lexical binding.

 ### New features

 Split up `parseSubscripts` to use an internal `parseSubscript` method to make it easier to extend with plugins.

 ## 6.0.7 (2019-02-04)

 ### Bug fixes

 Check that exported bindings are defined.

 Don't treat `\u180e` as a whitespace character.

 Check for duplicate parameter names in methods.

 Don't allow shorthand properties when they are generators or async methods.

 Forbid binding `await` in async arrow function's parameter list.

 ## 6.0.6 (2019-01-30)

 ### Bug fixes

 The content of class declarations and expressions is now always parsed in strict mode.

 Don't allow `let` or `const` to bind the variable name `let`.

 Treat class declarations as lexical.

 Don't allow a generator function declaration as the sole body of an `if` or `else`.

 Ignore `"use strict"` when after an empty statement.

 Allow string line continuations with special line terminator characters.

 Treat `for` bodies as part of the `for` scope when checking for conflicting bindings.

 Fix bug with parsing `yield` in a `for` loop initializer.

 Implement special cases around scope checking for functions.

 ## 6.0.5 (2019-01-02)

 ### Bug fixes

 Fix TypeScript type for `Parser.extend` and add `allowAwaitOutsideFunction` to options type.

 Don't treat `let` as a keyword when the next token is `{` on the next line.

 Fix bug that broke checking for parentheses around an object pattern in a destructuring assignment when `preserveParens` was on.

 ## 6.0.4 (2018-11-05)

 ### Bug fixes

 Further improvements to tokenizing regular expressions in corner cases.

 ## 6.0.3 (2018-11-04)

 ### Bug fixes

 Fix bug in tokenizing an expression-less return followed by a function followed by a regular expression.

 Remove stray symlink in the package tarball.

 ## 6.0.2 (2018-09-26)

 ### Bug fixes

 Fix bug where default expressions could fail to parse inside an object destructuring assignment expression.

 ## 6.0.1 (2018-09-14)

 ### Bug fixes

 Fix wrong value in `version` export.

 ## 6.0.0 (2018-09-14)

 ### Bug fixes

 Better handle variable-redefinition checks for catch bindings and functions directly under if statements.

 Forbid `new.target` in top-level arrow functions.

 Fix issue with parsing a regexp after `yield` in some contexts.

 ### New features

 The package now comes with TypeScript definitions.

 ### Breaking changes

 The default value of the `ecmaVersion` option is now 9 (2018).

 Plugins work differently, and will have to be rewritten to work with this version.

 The loose parser and walker have been moved into separate packages (`acorn-loose` and `acorn-walk`).

 ## 5.7.3 (2018-09-10)

 ### Bug fixes

 Fix failure to tokenize regexps after expressions like `x.of`.

 Better error message for unterminated template literals.

 ## 5.7.2 (2018-08-24)

 ### Bug fixes

 Properly handle `allowAwaitOutsideFunction` in for statements.

 Treat function declarations at the top level of modules like let bindings.

 Don't allow async function declarations as the only statement under a label.

 ## 5.7.0 (2018-06-15)

 ### New features

 Upgraded to Unicode 11.

 ## 5.6.0 (2018-05-31)

 ### New features

 Allow U+2028 and U+2029 in string when ECMAVersion >= 10.

 Allow binding-less catch statements when ECMAVersion >= 10.

 Add `allowAwaitOutsideFunction` option for parsing top-level `await`.

 ## 5.5.3 (2018-03-08)

 ### Bug fixes

 A _second_ republish of the code in 5.5.1, this time with yarn, to hopefully get valid timestamps.

 ## 5.5.2 (2018-03-08)

 ### Bug fixes

 A republish of the code in 5.5.1 in an attempt to solve an issue with the file timestamps in the npm package being 0.

 ## 5.5.1 (2018-03-06)

 ### Bug fixes

 Fix misleading error message for octal escapes in template strings.

 ## 5.5.0 (2018-02-27)

 ### New features

 The identifier character categorization is now based on Unicode version 10.

 Acorn will now validate the content of regular expressions, including new ES9 features.

 ## 5.4.0 (2018-02-01)

 ### Bug fixes

 Disallow duplicate or escaped flags on regular expressions.

 Disallow octal escapes in strings in strict mode.

 ### New features

 Add support for async iteration.

 Add support for object spread and rest.

 ## 5.3.0 (2017-12-28)

 ### Bug fixes

 Fix parsing of floating point literals with leading zeroes in loose mode.

 Allow duplicate property names in object patterns.

 Don't allow static class methods named `prototype`.

 Disallow async functions directly under `if` or `else`.

 Parse right-hand-side of `for`/`of` as an assignment expression.

 Stricter parsing of `for`/`in`.

 Don't allow unicode escapes in contextual keywords.

 ### New features

 Parsing class members was factored into smaller methods to allow plugins to hook into it.

 ## 5.2.1 (2017-10-30)

 ### Bug fixes

 Fix a token context corruption bug.

 ## 5.2.0 (2017-10-30)

 ### Bug fixes

 Fix token context tracking for `class` and `function` in property-name position.

 Make sure `%*` isn't parsed as a valid operator.

 Allow shorthand properties `get` and `set` to be followed by default values.

 Disallow `super` when not in callee or object position.

 ### New features

 Support [`directive` property](https://github.com/estree/estree/compare/b3de58c9997504d6fba04b72f76e6dd1619ee4eb...1da8e603237144f44710360f8feb7a9977e905e0) on directive expression statements.

 ## 5.1.2 (2017-09-04)

 ### Bug fixes

 Disable parsing of legacy HTML-style comments in modules.

 Fix parsing of async methods whose names are keywords.

 ## 5.1.1 (2017-07-06)

 ### Bug fixes

 Fix problem with disambiguating regexp and division after a class.

 ## 5.1.0 (2017-07-05)

 ### Bug fixes

 Fix tokenizing of regexps in an object-desctructuring `for`/`of` loop and after `yield`.

 Parse zero-prefixed numbers with non-octal digits as decimal.

 Allow object/array patterns in rest parameters.

 Don't error when `yield` is used as a property name.

 Allow `async` as a shorthand object property.

 ### New features

 Implement the [template literal revision proposal](https://github.com/tc39/proposal-template-literal-revision) for ES9.

 ## 5.0.3 (2017-04-01)

 ### Bug fixes

 Fix spurious duplicate variable definition errors for named functions.

 ## 5.0.2 (2017-03-30)

 ### Bug fixes

 A binary operator after a parenthesized arrow expression is no longer incorrectly treated as an error.

 ## 5.0.0 (2017-03-28)

 ### Bug fixes

 Raise an error for duplicated lexical bindings.

 Fix spurious error when an assignement expression occurred after a spread expression.

 Accept regular expressions after `of` (in `for`/`of`), `yield` (in a generator), and braced arrow functions.

 Allow labels in front or `var` declarations, even in strict mode.

 ### Breaking changes

 Parse declarations following `export default` as declaration nodes, not expressions. This means that class and function declarations nodes can now have `null` as their `id`.

 ## 4.0.11 (2017-02-07)

 ### Bug fixes

 Allow all forms of member expressions to be parenthesized as lvalue.

 ## 4.0.10 (2017-02-07)

 ### Bug fixes

 Don't expect semicolons after default-exported functions or classes, even when they are expressions.

 Check for use of `'use strict'` directives in non-simple parameter functions, even when already in strict mode.

 ## 4.0.9 (2017-02-06)

 ### Bug fixes

 Fix incorrect error raised for parenthesized simple assignment targets, so that `(x) = 1` parses again.

 ## 4.0.8 (2017-02-03)

 ### Bug fixes

 Solve spurious parenthesized pattern errors by temporarily erring on the side of accepting programs that our delayed errors don't handle correctly yet.

 ## 4.0.7 (2017-02-02)

 ### Bug fixes

 Accept invalidly rejected code like `(x).y = 2` again.

 Don't raise an error when a function _inside_ strict code has a non-simple parameter list.

 ## 4.0.6 (2017-02-02)

 ### Bug fixes

 Fix exponential behavior (manifesting itself as a complete hang for even relatively small source files) introduced by the new 'use strict' check.

 ## 4.0.5 (2017-02-02)

 ### Bug fixes

 Disallow parenthesized pattern expressions.

 Allow keywords as export names.

 Don't allow the `async` keyword to be parenthesized.

 Properly raise an error when a keyword contains a character escape.

 Allow `"use strict"` to appear after other string literal expressions.

 Disallow labeled declarations.

 ## 4.0.4 (2016-12-19)

 ### Bug fixes

 Fix crash when `export` was followed by a keyword that can't be
 exported.

 ## 4.0.3 (2016-08-16)

 ### Bug fixes

 Allow regular function declarations inside single-statement `if` branches in loose mode. Forbid them entirely in strict mode.

 Properly parse properties named `async` in ES2017 mode.

 Fix bug where reserved words were broken in ES2017 mode.

 ## 4.0.2 (2016-08-11)

 ### Bug fixes

 Don't ignore period or 'e' characters after octal numbers.

 Fix broken parsing for call expressions in default parameter values of arrow functions.

 ## 4.0.1 (2016-08-08)

 ### Bug fixes

 Fix false positives in duplicated export name errors.

 ## 4.0.0 (2016-08-07)

 ### Breaking changes

 The default `ecmaVersion` option value is now 7.

 A number of internal method signatures changed, so plugins might need to be updated.

 ### Bug fixes

 The parser now raises errors on duplicated export names.

 `arguments` and `eval` can now be used in shorthand properties.

 Duplicate parameter names in non-simple argument lists now always produce an error.

 ### New features

 The `ecmaVersion` option now also accepts year-style version numbers
 (2015, etc).

 Support for `async`/`await` syntax when `ecmaVersion` is >= 8.

 Support for trailing commas in call expressions when `ecmaVersion` is >= 8.

 ## 3.3.0 (2016-07-25)

 ### Bug fixes

 Fix bug in tokenizing of regexp operator after a function declaration.

 Fix parser crash when parsing an array pattern with a hole.

 ### New features

 Implement check against complex argument lists in functions that enable strict mode in ES7.

 ## 3.2.0 (2016-06-07)

 ### Bug fixes

 Improve handling of lack of unicode regexp support in host
 environment.

 Properly reject shorthand properties whose name is a keyword.

 ### New features

 Visitors created with `visit.make` now have their base as _prototype_, rather than copying properties into a fresh object.

 ## 3.1.0 (2016-04-18)

 ### Bug fixes

 Properly tokenize the division operator directly after a function expression.

 Allow trailing comma in destructuring arrays.

 ## 3.0.4 (2016-02-25)

 ### Fixes

 Allow update expressions as left-hand-side of the ES7 exponential operator.

 ## 3.0.2 (2016-02-10)

 ### Fixes

 Fix bug that accidentally made `undefined` a reserved word when parsing ES7.

 ## 3.0.0 (2016-02-10)

 ### Breaking changes

 The default value of the `ecmaVersion` option is now 6 (used to be 5).

 Support for comprehension syntax (which was dropped from the draft spec) has been removed.

 ### Fixes

 `let` and `yield` are now “contextual keywords”, meaning you can mostly use them as identifiers in ES5 non-strict code.

 A parenthesized class or function expression after `export default` is now parsed correctly.

 ### New features

 When `ecmaVersion` is set to 7, Acorn will parse the exponentiation operator (`**`).

 The identifier character ranges are now based on Unicode 8.0.0.

 Plugins can now override the `raiseRecoverable` method to override the way non-critical errors are handled.

 ## 2.7.0 (2016-01-04)

 ### Fixes

 Stop allowing rest parameters in setters.

 Disallow `y` rexexp flag in ES5.

 Disallow `\00` and `\000` escapes in strict mode.

 Raise an error when an import name is a reserved word.

 ## 2.6.2 (2015-11-10)

 ### Fixes

 Don't crash when no options object is passed.

 ## 2.6.0 (2015-11-09)

 ### Fixes

 Add `await` as a reserved word in module sources.

 Disallow `yield` in a parameter default value for a generator.

 Forbid using a comma after a rest pattern in an array destructuring.

 ### New features

 Support parsing stdin in command-line tool.

 ## 2.5.0 (2015-10-27)

 ### Fixes

 Fix tokenizer support in the command-line tool.

 Stop allowing `new.target` outside of functions.

 Remove legacy `guard` and `guardedHandler` properties from try nodes.

 Stop allowing multiple `__proto__` properties on an object literal in strict mode.

 Don't allow rest parameters to be non-identifier patterns.

 Check for duplicate paramter names in arrow functions.
	## 7.1.0 (2019-09-24)

	### Bug fixes

	Disallow trailing object literal commas when ecmaVersion is less than 5.

	### New features

	Add a static `acorn` property to the `Parser` class that contains the entire module interface, to allow plugins to access the instance of the library that they are acting on.

	## 7.0.0 (2019-08-13)

	### Breaking changes

	Changes the node format for dynamic imports to use the `ImportExpression` node type, as defined in [ESTree](https://github.com/estree/estree/blob/master/es2020.md#importexpression).

	Makes 10 (ES2019) the default value for the `ecmaVersion` option.

	## 6.3.0 (2019-08-12)

	### New features

	`sourceType: "module"` can now be used even when `ecmaVersion` is less than 6, to parse module-style code that otherwise conforms to an older standard.

	## 6.2.1 (2019-07-21)

	### Bug fixes

	Fix bug causing Acorn to treat some characters as identifier characters that shouldn't be treated as such.

	Fix issue where setting the `allowReserved` option to `"never"` allowed reserved words in some circumstances.

	## 6.2.0 (2019-07-04)

	### Bug fixes

	Improve valid assignment checking in `for`/`in` and `for`/`of` loops.

	Disallow binding `let` in patterns.

	### New features

	Support bigint syntax with `ecmaVersion` >= 11.

	Support dynamic `import` syntax with `ecmaVersion` >= 11.

	Upgrade to Unicode version 12.

	## 6.1.1 (2019-02-27)

	### Bug fixes

	Fix bug that caused parsing default exports of with names to fail.

	## 6.1.0 (2019-02-08)

	### Bug fixes

	Fix scope checking when redefining a `var` as a lexical binding.

	### New features

	Split up `parseSubscripts` to use an internal `parseSubscript` method to make it easier to extend with plugins.

	## 6.0.7 (2019-02-04)

	### Bug fixes

	Check that exported bindings are defined.

	Don't treat `\u180e` as a whitespace character.

	Check for duplicate parameter names in methods.

	Don't allow shorthand properties when they are generators or async methods.

	Forbid binding `await` in async arrow function's parameter list.

	## 6.0.6 (2019-01-30)

	### Bug fixes

	The content of class declarations and expressions is now always parsed in strict mode.

	Don't allow `let` or `const` to bind the variable name `let`.

	Treat class declarations as lexical.

	Don't allow a generator function declaration as the sole body of an `if` or `else`.

	Ignore `"use strict"` when after an empty statement.

	Allow string line continuations with special line terminator characters.

	Treat `for` bodies as part of the `for` scope when checking for conflicting bindings.

	Fix bug with parsing `yield` in a `for` loop initializer.

	Implement special cases around scope checking for functions.

	## 6.0.5 (2019-01-02)

	### Bug fixes

	Fix TypeScript type for `Parser.extend` and add `allowAwaitOutsideFunction` to options type.

	Don't treat `let` as a keyword when the next token is `{` on the next line.

	Fix bug that broke checking for parentheses around an object pattern in a destructuring assignment when `preserveParens` was on.

	## 6.0.4 (2018-11-05)

	### Bug fixes

	Further improvements to tokenizing regular expressions in corner cases.

	## 6.0.3 (2018-11-04)

	### Bug fixes

	Fix bug in tokenizing an expression-less return followed by a function followed by a regular expression.

	Remove stray symlink in the package tarball.

	## 6.0.2 (2018-09-26)

	### Bug fixes

	Fix bug where default expressions could fail to parse inside an object destructuring assignment expression.

	## 6.0.1 (2018-09-14)

	### Bug fixes

	Fix wrong value in `version` export.

	## 6.0.0 (2018-09-14)

	### Bug fixes

	Better handle variable-redefinition checks for catch bindings and functions directly under if statements.

	Forbid `new.target` in top-level arrow functions.

	Fix issue with parsing a regexp after `yield` in some contexts.

	### New features

	The package now comes with TypeScript definitions.

	### Breaking changes

	The default value of the `ecmaVersion` option is now 9 (2018).

	Plugins work differently, and will have to be rewritten to work with this version.

	The loose parser and walker have been moved into separate packages (`acorn-loose` and `acorn-walk`).

	## 5.7.3 (2018-09-10)

	### Bug fixes

	Fix failure to tokenize regexps after expressions like `x.of`.

	Better error message for unterminated template literals.

	## 5.7.2 (2018-08-24)

	### Bug fixes

	Properly handle `allowAwaitOutsideFunction` in for statements.

	Treat function declarations at the top level of modules like let bindings.

	Don't allow async function declarations as the only statement under a label.

	## 5.7.0 (2018-06-15)

	### New features

	Upgraded to Unicode 11.

	## 5.6.0 (2018-05-31)

	### New features

	Allow U+2028 and U+2029 in string when ECMAVersion >= 10.

	Allow binding-less catch statements when ECMAVersion >= 10.

	Add `allowAwaitOutsideFunction` option for parsing top-level `await`.

	## 5.5.3 (2018-03-08)

	### Bug fixes

	A _second_ republish of the code in 5.5.1, this time with yarn, to hopefully get valid timestamps.

	## 5.5.2 (2018-03-08)

	### Bug fixes

	A republish of the code in 5.5.1 in an attempt to solve an issue with the file timestamps in the npm package being 0.

	## 5.5.1 (2018-03-06)

	### Bug fixes

	Fix misleading error message for octal escapes in template strings.

	## 5.5.0 (2018-02-27)

	### New features

	The identifier character categorization is now based on Unicode version 10.

	Acorn will now validate the content of regular expressions, including new ES9 features.

	## 5.4.0 (2018-02-01)

	### Bug fixes

	Disallow duplicate or escaped flags on regular expressions.

	Disallow octal escapes in strings in strict mode.

	### New features

	Add support for async iteration.

	Add support for object spread and rest.

	## 5.3.0 (2017-12-28)

	### Bug fixes

	Fix parsing of floating point literals with leading zeroes in loose mode.

	Allow duplicate property names in object patterns.

	Don't allow static class methods named `prototype`.

	Disallow async functions directly under `if` or `else`.

	Parse right-hand-side of `for`/`of` as an assignment expression.

	Stricter parsing of `for`/`in`.

	Don't allow unicode escapes in contextual keywords.

	### New features

	Parsing class members was factored into smaller methods to allow plugins to hook into it.

	## 5.2.1 (2017-10-30)

	### Bug fixes

	Fix a token context corruption bug.

	## 5.2.0 (2017-10-30)

	### Bug fixes

	Fix token context tracking for `class` and `function` in property-name position.

	Make sure `%*` isn't parsed as a valid operator.

	Allow shorthand properties `get` and `set` to be followed by default values.

	Disallow `super` when not in callee or object position.

	### New features

	Support [`directive` property](https://github.com/estree/estree/compare/b3de58c9997504d6fba04b72f76e6dd1619ee4eb...1da8e603237144f44710360f8feb7a9977e905e0) on directive expression statements.

	## 5.1.2 (2017-09-04)

	### Bug fixes

	Disable parsing of legacy HTML-style comments in modules.

	Fix parsing of async methods whose names are keywords.

	## 5.1.1 (2017-07-06)

	### Bug fixes

	Fix problem with disambiguating regexp and division after a class.

	## 5.1.0 (2017-07-05)

	### Bug fixes

	Fix tokenizing of regexps in an object-desctructuring `for`/`of` loop and after `yield`.

	Parse zero-prefixed numbers with non-octal digits as decimal.

	Allow object/array patterns in rest parameters.

	Don't error when `yield` is used as a property name.

	Allow `async` as a shorthand object property.

	### New features

	Implement the [template literal revision proposal](https://github.com/tc39/proposal-template-literal-revision) for ES9.

	## 5.0.3 (2017-04-01)

	### Bug fixes

	Fix spurious duplicate variable definition errors for named functions.

	## 5.0.2 (2017-03-30)

	### Bug fixes

	A binary operator after a parenthesized arrow expression is no longer incorrectly treated as an error.

	## 5.0.0 (2017-03-28)

	### Bug fixes

	Raise an error for duplicated lexical bindings.

	Fix spurious error when an assignement expression occurred after a spread expression.

	Accept regular expressions after `of` (in `for`/`of`), `yield` (in a generator), and braced arrow functions.

	Allow labels in front or `var` declarations, even in strict mode.

	### Breaking changes

	Parse declarations following `export default` as declaration nodes, not expressions. This means that class and function declarations nodes can now have `null` as their `id`.

	## 4.0.11 (2017-02-07)

	### Bug fixes

	Allow all forms of member expressions to be parenthesized as lvalue.

	## 4.0.10 (2017-02-07)

	### Bug fixes

	Don't expect semicolons after default-exported functions or classes, even when they are expressions.

	Check for use of `'use strict'` directives in non-simple parameter functions, even when already in strict mode.

	## 4.0.9 (2017-02-06)

	### Bug fixes

	Fix incorrect error raised for parenthesized simple assignment targets, so that `(x) = 1` parses again.

	## 4.0.8 (2017-02-03)

	### Bug fixes

	Solve spurious parenthesized pattern errors by temporarily erring on the side of accepting programs that our delayed errors don't handle correctly yet.

	## 4.0.7 (2017-02-02)

	### Bug fixes

	Accept invalidly rejected code like `(x).y = 2` again.

	Don't raise an error when a function _inside_ strict code has a non-simple parameter list.

	## 4.0.6 (2017-02-02)

	### Bug fixes

	Fix exponential behavior (manifesting itself as a complete hang for even relatively small source files) introduced by the new 'use strict' check.

	## 4.0.5 (2017-02-02)

	### Bug fixes

	Disallow parenthesized pattern expressions.

	Allow keywords as export names.

	Don't allow the `async` keyword to be parenthesized.

	Properly raise an error when a keyword contains a character escape.

	Allow `"use strict"` to appear after other string literal expressions.

	Disallow labeled declarations.

	## 4.0.4 (2016-12-19)

	### Bug fixes

	Fix crash when `export` was followed by a keyword that can't be
	exported.

	## 4.0.3 (2016-08-16)

	### Bug fixes

	Allow regular function declarations inside single-statement `if` branches in loose mode. Forbid them entirely in strict mode.

	Properly parse properties named `async` in ES2017 mode.

	Fix bug where reserved words were broken in ES2017 mode.

	## 4.0.2 (2016-08-11)

	### Bug fixes

	Don't ignore period or 'e' characters after octal numbers.

	Fix broken parsing for call expressions in default parameter values of arrow functions.

	## 4.0.1 (2016-08-08)

	### Bug fixes

	Fix false positives in duplicated export name errors.

	## 4.0.0 (2016-08-07)

	### Breaking changes

	The default `ecmaVersion` option value is now 7.

	A number of internal method signatures changed, so plugins might need to be updated.

	### Bug fixes

	The parser now raises errors on duplicated export names.

	`arguments` and `eval` can now be used in shorthand properties.

	Duplicate parameter names in non-simple argument lists now always produce an error.

	### New features

	The `ecmaVersion` option now also accepts year-style version numbers
	(2015, etc).

	Support for `async`/`await` syntax when `ecmaVersion` is >= 8.

	Support for trailing commas in call expressions when `ecmaVersion` is >= 8.

	## 3.3.0 (2016-07-25)

	### Bug fixes

	Fix bug in tokenizing of regexp operator after a function declaration.

	Fix parser crash when parsing an array pattern with a hole.

	### New features

	Implement check against complex argument lists in functions that enable strict mode in ES7.

	## 3.2.0 (2016-06-07)

	### Bug fixes

	Improve handling of lack of unicode regexp support in host
	environment.

	Properly reject shorthand properties whose name is a keyword.

	### New features

	Visitors created with `visit.make` now have their base as _prototype_, rather than copying properties into a fresh object.

	## 3.1.0 (2016-04-18)

	### Bug fixes

	Properly tokenize the division operator directly after a function expression.

	Allow trailing comma in destructuring arrays.

	## 3.0.4 (2016-02-25)

	### Fixes

	Allow update expressions as left-hand-side of the ES7 exponential operator.

	## 3.0.2 (2016-02-10)

	### Fixes

	Fix bug that accidentally made `undefined` a reserved word when parsing ES7.

	## 3.0.0 (2016-02-10)

	### Breaking changes

	The default value of the `ecmaVersion` option is now 6 (used to be 5).

	Support for comprehension syntax (which was dropped from the draft spec) has been removed.

	### Fixes

	`let` and `yield` are now “contextual keywords”, meaning you can mostly use them as identifiers in ES5 non-strict code.

	A parenthesized class or function expression after `export default` is now parsed correctly.

	### New features

	When `ecmaVersion` is set to 7, Acorn will parse the exponentiation operator (`**`).

	The identifier character ranges are now based on Unicode 8.0.0.

	Plugins can now override the `raiseRecoverable` method to override the way non-critical errors are handled.

	## 2.7.0 (2016-01-04)

	### Fixes

	Stop allowing rest parameters in setters.

	Disallow `y` rexexp flag in ES5.

	Disallow `\00` and `\000` escapes in strict mode.

	Raise an error when an import name is a reserved word.

	## 2.6.2 (2015-11-10)

	### Fixes

	Don't crash when no options object is passed.

	## 2.6.0 (2015-11-09)

	### Fixes

	Add `await` as a reserved word in module sources.

	Disallow `yield` in a parameter default value for a generator.

	Forbid using a comma after a rest pattern in an array destructuring.

	### New features

	Support parsing stdin in command-line tool.

	## 2.5.0 (2015-10-27)

	### Fixes

	Fix tokenizer support in the command-line tool.

	Stop allowing `new.target` outside of functions.

	Remove legacy `guard` and `guardedHandler` properties from try nodes.

	Stop allowing multiple `__proto__` properties on an object literal in strict mode.

	Don't allow rest parameters to be non-identifier patterns.

	Check for duplicate paramter names in arrow functions.