Add EmbeddedWorker interfaces in Blink API

Rough design doc: https://docs.google.com/a/chromium.org/document/d/1HzjaXttZcRr6cE7oINMzvlVskbGpGnB_Tn37ayjST9Q/edit

Chromium-side patch: https://codereview.chromium.org/54573002/

BUG=313530

Review URL: https://codereview.chromium.org/61763004

git-svn-id: svn://svn.chromium.org/blink/trunk@162282 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[DevTools] Don't recommend gzip cached resources in audit.

Cached resources loose some information, e.g. that they were compressed.
So we are to exclude them from 'gzip' recommendations.

BUG=314096
R=aandrey@chromium.org

Review URL: https://codereview.chromium.org/69813012

git-svn-id: svn://svn.chromium.org/blink/trunk@162283 bbb929c8-8fbe-4397-9dbb-9b2b20218538