Remove fragment as well as the query from URLs when resolving MIME type

When we try to deduce the MIME type from the file extension of
a URL, strip the fragment off at the same time we are stripping
the query. Otherwise we end up trying to match against some
funny extensions.

Bug:3241908

Change-Id: Ibaa84f0a628f37cd012b6cfbed9a6a666ecae8bb