WebCrypto: Properly normalize algorithm for importKey().

HMAC should retain the "hash" parameters after normalization.

This corresponds with the spec update: https://dvcs.w3.org/hg/webcrypto-api/rev/5cf8db70af2e


BUG=245025

Review URL: https://chromiumcodereview.appspot.com/20475004

git-svn-id: svn://svn.chromium.org/blink/trunk@155297 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add forceLayout and forceChildLayout.

The only time when it's safe to call setNeedsLayout(..., MarkOnlyThis)
is when we are 100% sure we'll call layout. Add functions to do this
to get us incrementally towards fewer MarkOnlyThis locations.

I'm not convinced that we need both these functions, but I wanted
to be 100% sure I'm not changing behavior in this patch.

Review URL: https://chromiumcodereview.appspot.com/21106010

git-svn-id: svn://svn.chromium.org/blink/trunk@155298 bbb929c8-8fbe-4397-9dbb-9b2b20218538