DEBUG build is not compatible with IE8

[bcowgill]

First of all, thanks a million for making this IE8 compatible react repository available. We're in route to production and suddenly told that we have to support IE8 because the business hasn't completed it's IE8 decommissioning project on time.

The issue I've noticed is if you do the debug build yarn build:debug then the app fails to load in IE8.
I get Expected Identifier error in vendor bundle

 if (true) {
    var REACT_ELEMENT_TYPE = (typeof Symbol === 'function' &&
===>      Symbol.for &&

And Expected identifier, string or number in main bundle

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
must be the default: obj

I found If I always to the Uglify call then it works...

if (!DEBUG) {
  config.plugins.push(new webpack.optimize.DedupePlugin())
}
// Must always be done or it won't work in IE8
  config.plugins.push(new webpack.optimize.UglifyJsPlugin({
    compress: { warnings: VERBOSE, screw_ie8: false },
    mangle: { screw_ie8: false },
    output: { screw_ie8: false },
  }))
if (!DEBUG) {
  config.plugins.push(new webpack.optimize.AggressiveMergingPlugin())
  config.module.loaders
    .find(x => x.loader === 'babel-loader').query.plugins
    .unshift(
    'transform-react-remove-prop-types',
    'transform-react-constant-elements',
    'transform-react-inline-elements',
    'transform-es3-modules-literals',
    'transform-es3-member-expression-literals',
    'transform-es3-property-literals'
    )
}

I tried changing it so it didn't compress or mangle, but still did the output screw_ie8 but that caused the same problem.

[bcowgill]

I have a fix. Just need to use different options to the Uglify when debugging. Must still compress, but don't mangle and beautify the output again.

// Optimize the bundle in release (production) mode
if (!DEBUG) {
  config.plugins.push(new webpack.optimize.DedupePlugin())
}

// Must always Uglify somehow or it won't work in IE8
const uglyOptions = !DEBUG ? {
  compress: {
    warnings: VERBOSE,
    typeofs: false, // suggested for IE10 or less
    screw_ie8: false
  },
  mangle: { screw_ie8: false },
  output: { screw_ie8: false }
} : {
  mangle: false,
  compress: {
    drop_debugger: false,
/* could set lots more settings false to leave the code as is. */
    typeofs: false, // suggested for IE10 or less
    warnings: VERBOSE,
    screw_ie8: false
  },
  output: {
    beautify: true,
    comments: true,
    bracketize: true,
    indent_level: 2,
    keep_quoted_props: true,
/* more settings to your liking... */
    screw_ie8: false
  },
};
config.plugins.push(new webpack.optimize.UglifyJsPlugin(uglyOptions))

if (!DEBUG) {
  config.plugins.push(new webpack.optimize.AggressiveMergingPlugin())
  config.module.loaders
    .find(x => x.loader === 'babel-loader').query.plugins
    .unshift(
    'transform-react-remove-prop-types',
    'transform-react-constant-elements',
    'transform-react-inline-elements',
    'transform-es3-modules-literals',
    'transform-es3-member-expression-literals',
    'transform-es3-property-literals'
    )
}

[copilot-is]

Thank you.
Fix 4c38aef