Fix crash when focus-navigating to a shadow insertion point in the oldest shadow tree.

Shadow insertion points in the oldest shadow tree should not be treated as a focus scope owner.

The relevant spec is: http://w3c.github.io/webcomponents/spec/shadow/#focus-navigation

BUG=336289

Review URL: https://codereview.chromium.org/143643004

git-svn-id: svn://svn.chromium.org/blink/trunk@165476 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Use UNLIKELY in spinLockLock to denote contention as the unlikely case.

This ensures that the machine jump instruction is not taken for the common case
of no contention.

Review URL: https://codereview.chromium.org/131023005

git-svn-id: svn://svn.chromium.org/blink/trunk@165477 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[webcrypto] Delete some deprecated code.

BUG=245025
TBR=abarth

Review URL: https://codereview.chromium.org/141073008

git-svn-id: svn://svn.chromium.org/blink/trunk@165478 bbb929c8-8fbe-4397-9dbb-9b2b20218538