Prevent URLs with invalid schemes from resolving as relative to data: URLs.

There is a missing bit of logic when the scheme is invalid that is
present in the case where the scheme is empty.  Either way, we can't
consider this a relative URL if the base scheme isn't heirarchical.

BUG=346132

Review URL: https://codereview.chromium.org/177093008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254565 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254565