ServiceWorker: Registering a malformed script should fail [1/3]

Before this series of patches, registration succeeds even if the worker script
has a syntax error because the installing sequence does not check the result of
the script evaluation.

To enable the installing sequence to wait for the script evaluation, this adds
WorkerReportingProxy::didEvaluteWorkerScript() to be called when the
evaluation is completed and to propagate the result up to the Chromium-side.

Patch dependency:
[1] Blink: THIS PATCH
[2] Chromium: https://codereview.chromium.org/697593002/
[3] Blink: https://codereview.chromium.org/697833004/

BUG=426344
TEST=compile (test will be added by [3])

Review URL: https://codereview.chromium.org/692003002

git-svn-id: svn://svn.chromium.org/blink/trunk@184854 bbb929c8-8fbe-4397-9dbb-9b2b20218538