Update ServiceWorkerProviderHost when the pending version changes
When ServiceWorkerRegisterJob changes a registration's pending version, iterate
over all existing ServiceWorkerProviderHost and update their pending version,
if they are in-scope for the registration. This will enable documents to have
an up-to-date navigator.serviceWorker.pending object, but that is not yet
implemented (and will probably be renamed to next or installing).
BUG=361565
Review URL: https://codereview.chromium.org/
238823002
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@264164 0039d316-1c4b-4281-b951-d872f2087c98