[whatwg] Adding 2D Canvas features

[Simon Sarris]

Just FYI, Chrome now has a relatively new bug for "Canvas v5 API additions"
that references all the missing features that some posters were concerned
about.

The default take from this bug report is that all of these are greenlighted
to be worked on (no objections so far)

https://code.google.com/p/chromium/issues/detail?id=281529

This bug is now (as of a few days ago) referenced at chromestatus.com under
the Canvas feature's implementation status:

http://www.chromestatus.com/features/5100084685438976

Simon