src/third_party/mozjs-45/js/src/jit-test/tests/ion/bug732863.js

// Compiled
function TestCase(a) { }

// Not compiled (try)
function reportCompare (actual) {
  TestCase(actual);
  try   {  }  catch(ex)  {  }
}

// Compiled
function addThis(bound) {
    actualvalues[bound] = undefined + actual;
    reportCompare(actualvalues[bound]);
}

var actual = '';
var actualvalues = [];
addThis(0);
actual = NaN;
addThis(1);