Whitelist and scanning for %TypedArray%.{from,of} methods.

* Whitelist %TypedArray%.from and %TypedArray%.of (or the same methods
  on the individual array constructors, as currently implemented in
  Chrome).
* Add scan coverage for those methods.

Unrelated but needed to be done:
* Add missing always-throws declaration for generator throw method.

@ f383681cece31b6f3160b791485e58bf2f18779c

[MarkM, 2015-07-23 19:12:17]

LGTM