Rebaseline canvas2d-api-changes.html

The newly added API methods need to be investigated.

BUG=
TBR=aandrey

Review URL: https://codereview.chromium.org/332343009

git-svn-id: svn://svn.chromium.org/blink/trunk@177229 bbb929c8-8fbe-4397-9dbb-9b2b20218538