Document unsupported plugins

[goldhand]

There are a few issues using some unsupported plugins (particularly commons). It would be nice to document unsupported plugins and possibly provide an example that separates a webpack test config eloquently.

Issues mentioning unsupported plugins:

• Commons: Using CommonsChunkPlugin #22, CommonsChunkPlugin and "Path doesn't exist " error #91
• ExtractText: Unable to include CSS generated by webpack ExtractTextPlugin #133

[joshwiens]

Sticking this here as a note for after we have proper code validations in place.

In regards to Commons, @wied03 took a rather elegant approach in which he first normalized the entry points thus supporting the use of commons-chunk which at least appears to be a feature people are interested in.

https://github.com/wied03/karma_webpack_2/blob/376fe55720ab9eb7a368d1a610c6867b98ec133c/lib/index.js#L53-L57

At minimum, it's worth further discussion at the appropriate time.

[aindlq]

It is also not possible to use Webpack DLL plugin, I think the reason is the same as for CommonsChunk plugin.

[frankandrobot]

Wait wat? Webpack DLL is unsupported? Is this still true with webpack 2?