[2dcontext-tests][html-tests] Add coverage for blend operations (#1822)

@KyleFung and I from Mozilla have been working on adding coverage for blend operations to Philip Taylor's compositing tests. Please let us know if there are any changes to be made!

View on GitHub: https://github.com/w3c/web-platform-tests/pull/1822

Received on Tuesday, 12 May 2015 18:12:00 UTC