Support ES6 classes syntax with working coverage

[nkbt]

The issue appears in coverage. Everything usually works fine, but coverage is kind of broken because of transpiling:

There is a solution:

But it does not fix everything unfortunately:

[nkbt]

Probably this outstanding branch check could be fixed by adding some additional test for component itself. Will play a bit more with it.

[nkbt]

Hmm, Firefox Dev edition supports Classes syntax if used with

<script type="application/javascript;version=1.7"> (or version=1.8) tag.

http://kangax.github.io/compat-table/es6/#class

So the possible solution could be to use Firefox Dev edition and disable bunch of BabelJS transpiling options, so the code for instrumenter will be coming mostly untouched.

[nkbt]

I tried to avoid extra transformations using babel's blacklist option and Firefox Dev Edition. Import/export is not yet supported anywhere, so I blacklisted only classes. Classes are supported only with <script type="application/javascript;version=1.7"> so I modified karma's internal html.

Another problem was that webpack does not support es6 and gives compilation errors, when it sees class. That could be fixed by using npm install webpack/webpack#webpack-2 branch which uses acorn parser and does not fail horribly anymore.

After all things I still could not get the coverage report, though doing normal webpack compilation worked and Firefox Dev was showing working site as expected.

That does not look like a working solution anyway :(

[nkbt]

Oh, yes! It is solved with https://github.com/deepsweet/isparta-loader

Beautiful

All fixed with 2e90d07