ES6 Final Tweaks

[inexorabletash]

Per https://twitter.com/awbjs

• ES6 WeakMap and WeakSet clear methods eliminated
• ES6 final tweaks Document bindata #2: String.prototype.contains renamed to String.prototype.includes
• ES6 final tweaks Subsume DOMURL functions #3: Symbols @@match, @@replace, @@search, @@split replace string names as double dispatch targets in RegExp.prototype
• ES6 final tweak Convert index.html to README.md #4: added RegExp.prototype.flags for accessing flags string. Facilitates RegExp subclasses that add flags.
• ES6 final tweaks iteration over Map #5: new RegExp(aRegExp, flags) no longer throws. Instead clones first argument but with supplied flags.
  • Can't usefully polyfill a constructor
• ES6 final tweaks Storage should be replaced by fork of https://github.com/wojodesign/local-storage-js #6: at the top level of a module, the this binding evaluates to undefined.
  • Can't polyfill modules
• ES6 final tweaks Uint8Array crashes IE9 #7: Array.isArray(new Proxy([ ], { })) returns true.
  • Can't polyfill proxies
• ES6 final tweaks ES6: Remove Number.toInteger #8: Smalltalk-like species pattern used in Array methods, etc. to determine constructor for derived objects. let derived = new obj.constructor.species();

[inexorabletash]

Re: @@match and friends - the point is that calling: "abc".match(re) should now work if re is a regular expression subclass, because String.prototype.match will delegate to re[@@match]. That implies hooking String.prototype.match (etc) in the polyfill.

[inexorabletash]

I'll probably wait on @@species until it hits a draft.

[inexorabletash]

I did a pass to synchronize with the latest draft. The guts of Promise methods abstract operations need a bit more alignment, but overall I think it's in good shape.

I still have not tackled @@species - pull requests (including tests!) welcome.