Revert of Revert of Service Worker: Add tests for same-scope new script registration (patchset #1 id:1 of https://codereview.chromium.org/512703002/)

Reason for revert:
This crash will be fixed by https://codereview.chromium.org/556003006.

Original issue's description:
> Revert of Service Worker: Add tests for same-scope new script registration (patchset #6 of https://codereview.chromium.org/480943002/)
> 
> Reason for revert:
> This is crashing on Mac.
> 
> Original issue's description:
> > Service Worker: Add tests for same-scope, new script registration
> > 
> > Tests for Chromium patch:
> > https://codereview.chromium.org/506043002/
> > 
> > BUG=398355
> > 
> > Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=180948
> 
> TBR=michaeln@chromium.org,nhiroki@chromium.org,falken@chromium.org
> NOTREECHECKS=true
> NOTRY=true
> BUG=398355
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=180956

TBR=michaeln@chromium.org,nhiroki@chromium.org,falken@chromium.org,mlamouri@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=398355

Review URL: https://codereview.chromium.org/547743003

git-svn-id: svn://svn.chromium.org/blink/trunk@181878 bbb929c8-8fbe-4397-9dbb-9b2b20218538