Add [TypeChecking=Unrestricted] to CanvasRenderingContext2D

Fixes all double/float type-checking in CanvasRenderingContext2D!

(Also remove outdated tests in canvas/philip/tests, as before.)

R=haraken
R=fs
BUG=354298
BUG=367648
TEST=run_webkit_tests.sh fast/canvas canvas

Review URL: https://codereview.chromium.org/263563007

git-svn-id: svn://svn.chromium.org/blink/trunk@172960 bbb929c8-8fbe-4397-9dbb-9b2b20218538