Speculative fix for resource-timing-details-for-revalidation.html

It seems that the resource timing entries for web fonts aren't always
available at the time the fonts.ready() promise is resolved. Check the
resorce timing entris for web fonts after a short delay.

BUG=372214

Review URL: https://codereview.chromium.org/273403002

git-svn-id: svn://svn.chromium.org/blink/trunk@173850 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Initializes the context of WorkerScriptController before calling willEvaluateWorkerScript.

This change will fix the crash bug on Debug build while reattaching DevTools to SharedWorker and dedicated worker.
See: https://code.google.com/p/chromium/issues/detail?id=371399#c8

BUG=371399

Review URL: https://codereview.chromium.org/270873005

git-svn-id: svn://svn.chromium.org/blink/trunk@173851 bbb929c8-8fbe-4397-9dbb-9b2b20218538