Add WebKit tests

[jwal]

The new feature does not have any tests, add something

[jwal]

Canvas tests, although included as part of the upstream WebKit GIT repository seem to be maintained in Hg, here:
http://dvcs.w3.org/hg/html/file/1d30da826739/tests/approved/canvas

[jwal]

There are some examples that might be useful as tests here: https://github.com/jwal/webkit/wiki/fillRule-specification

[jwal]

My work-in-progress for this is here: https://github.com/jwal/html-testsuite/compare/master