Rename InstallPhaseEvent to ExtendableEvent.

Change Exposed=ServiceWorker for all ServiceWorker events.
Move Func= exposure check to ServiceWorker.

--HG--
rename : dom/webidl/InstallPhaseEvent.webidl => dom/webidl/ExtendableEvent.webidl
extra : rebase_source : 81371e622493fed1a22e1f50590efd06dfc0b2d3
Bug 1039846 - Patch 5: Basic HTTP fetch and delayed body reading. r=baku

The promise returned by a call to a body reading method (e.g. text()) now waits on a complete stream if one isn't available.

--HG--
extra : rebase_source : 13f9a58d01163fbae146124bfb508db1f3dc8ff1
Bug 1039846 - Set up request headers and  body upload stream. r=baku

--HG--
extra : rebase_source : 74ddd76363722590e5f93fb472ef943e0d004533
Bug 1039846 - Patch 6: Use readSegments to read Fetch body streams. r=baku

--HG--
extra : rebase_source : c15355892766bbd483d6ff41c1d96e94efba3588