Correcting `String.raw` to follow ES6 spec step 14.h.
Ensure that Set#keys is the same object as Set#values.

Per https://people.mozilla.org/~jorendorff/es6-draft.html#sec-set.prototype.keys
In `{Set,Map}#forEach` and `Array#find{,Index}`, don't use Function#call unless a context is provided.