Add platform/WebConvertableToTraceFormat.h

This is extracted from https://codereview.chromium.org/236983003/
to provide the types necessary to land the chromium counterpart in
https://codereview.chromium.org/236683007/

BUG=361045
TBR=pfeldman

Review URL: https://codereview.chromium.org/240333004

git-svn-id: svn://svn.chromium.org/blink/trunk@171788 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[webcrypto] Update layout tests to match idl generator changes.

Functions that return Promises no longer throw TypeError exceptions.

BUG=362992,245025

Review URL: https://codereview.chromium.org/240063002

git-svn-id: svn://svn.chromium.org/blink/trunk@171789 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Use StrictTypeChecking for ImageBitmap

Add [StrictTypeChecking] to the 'ImageBitmapFactories' interface and
the 'Window' partial interface. This doesn't change behavior in practice,
but signals that it has been considered.
Drop the unnecessary null-checks in the implementation.

Review URL: https://codereview.chromium.org/240103002

git-svn-id: svn://svn.chromium.org/blink/trunk@171790 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Don't parse colors for <canvas> in quirks mode

Use 'strict' mode when parsing colors, to disallow hex-color
specifications without a leading '#'.

BUG=364008

Review URL: https://codereview.chromium.org/237743009

git-svn-id: svn://svn.chromium.org/blink/trunk@171791 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add repaint tests on window resize

Though before bug 258219 is fixed, all window resizes trigger full repaint,
the tests cover cases needing proper repaint on window resizes. Some also
cover failures caused by previous patches for bug 258219.

Will update expectations after bug 258219 is fixed. Should carefully examine
possible under-repaints.

BUG=258219,362407

Review URL: https://codereview.chromium.org/236073002

git-svn-id: svn://svn.chromium.org/blink/trunk@171792 bbb929c8-8fbe-4397-9dbb-9b2b20218538