Move mutation processing into it's own class

[eoghanmurray]

This should stand on it's own as a refactor, but is intended as a basis
for exposing the new MutationBuffer object to further outside control e.g.
to 'mute' or batch up mutation emission when the page becomes inactive
from a https://developer.mozilla.org/en-US/docs/Web/API/Page_Visibility_API
point of view

[eoghanmurray]

Not currently working; output is producing this:

MutationBuffer.prototype.processMutations = function (mutations) {
   ...
   var _this = this;
   mutations.forEach(this.processMutation);

instead of

mutations.forEach(_this.processMutation);

[eoghanmurray]

Ok, working now with the 05334ef commit.

[eoghanmurray]

Have solved the bind problem by making all methods use the Arrow function expressions.
Let me know if there's a neater way of doing methods (with the ability to use this) in typescript.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions

https://stackoverflow.com/questions/43724426/this-is-undefined-inside-the-foreach-loop

[Yuyz0112]

@eoghanmurray The changes look good to me.

If I'm right, this patch is a 1-1 rewrite of the mutation processing code without any new logic and would be the base of the following changes.

Please let me know if I'm wrong. For example, if there are any logical changes to the processing flow and I would like to review that part again.

(I've already go through the patch, but Github's split view was not quite useful for comparing new files and deleted files)

[eoghanmurray]

Yes, this mutationClass branch is purely refactoring, and should not have any logical changes. Apologies for delay.

[eoghanmurray]

#224 builds on top of this and has the logical changes discussed in #221 .

[Yuyz0112]

@eoghanmurray Thanks for the feedback, I would love to merge this patch and start to review the next one.