Add a ScriptForbiddenScope to ContainerNode::appendChild

We should never execute script inside the inner part of the loop, lets
add a ScriptForbiddenScope in addition to the NoEventDispatchAssertion.

Review URL: https://codereview.chromium.org/301823005

git-svn-id: svn://svn.chromium.org/blink/trunk@175035 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove canvas.drawCustomFocusRing()

The method was removed from the HTML Canvas2D Context Level 1 Specification:
  http://www.w3.org/html/wg/drafts/2dcontext/html5_canvas_CR#removals

Review URL: https://codereview.chromium.org/289283019

git-svn-id: svn://svn.chromium.org/blink/trunk@175036 bbb929c8-8fbe-4397-9dbb-9b2b20218538