ServiceWorker: Remove a fragment from document url on getRegistration

A fragment part does not make sense for registration match, so that should be
removed in advance.

BUG=428451
TEST=run-webkit-tests --debug http/tests/serviceworker

Review URL: https://codereview.chromium.org/688783002

git-svn-id: svn://svn.chromium.org/blink/trunk@184623 bbb929c8-8fbe-4397-9dbb-9b2b20218538