Compatibility issues in tests

[maxbarnas]

Related: #312.

[maxbarnas]

Currently, I added fake polyfill for String.prototype.normalize() to check if it is the real problem in Safari 9. Real, working alternative to this is https://github.com/walling/unorm, but it is around 140 kB. I am open to suggestions. Maybe there is already some package in CKEditor 5, that solves this problem.

I also highlighted problematic tests with // x comment, and will deal with them now.

[Reinmar]

cc @scofalik – he mentioned that that normalization isn't necessary (or something similar :)).

[scofalik]

We can remove normalization for now.

So there should not be .normalize() both in code and in tests. BTW. this may make some test returning wrong results. If that happens, contact me.

[Reinmar]

@maxbarnas found also some issue with regexps. Could you elaborate on that, @maxbarnas? Perhaps @scofalik will be able to help you. I only know that ES6 added support for multi-byte chars in regexps, so perhaps their transpilation fails somehow... but OTOH, it should make tests fail.

[maxbarnas]

@scofalik I explained the problem a little in https://github.com/ckeditor/ckeditor5-utils/issues/66#issuecomment-242045302

[Reinmar]

This issue covered only a part of problems. There's a followup in #325.