Add ScriptForbiddenScopes to style and layout.

After r177267 script should never run inside updateRenderTree or inside
updateLayout except for plugins and the inspector. Lets add some asserts
to make sure that it stays that way.

BUG=356487

Review URL: https://codereview.chromium.org/367863002

git-svn-id: svn://svn.chromium.org/blink/trunk@177455 bbb929c8-8fbe-4397-9dbb-9b2b20218538