Add ServiceWorker InstallPhaseEvent.waitUntil() layout test.
    
Add InstallPhaseEvent layout tests for both "install" and "activate" events.

Fix the rejection precedence when multiple promises waiting on an event.

Rename the "active" state to "activated" and "deactivated" state to "redundant", see:
https://slightlyoff.github.io/ServiceWorker/spec/service_worker/#service-worker-state.

BUG=375132
TEST=http/tests/serviceworker/install-phase-event-waituntil.html

Review URL: https://codereview.chromium.org/352423005

git-svn-id: svn://svn.chromium.org/blink/trunk@177461 bbb929c8-8fbe-4397-9dbb-9b2b20218538