Percent-encode UTF8 characters in URL fragment identifiers.

This brings us into line with Firefox, Safari, and the spec.

Bug: 758523
Change-Id: I7e354ab441222d9fd08e45f0e70f91ad4e35fafe
Reviewed-on: https://chromium-review.googlesource.com/668363
Commit-Queue: Mike West <mkwst@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Andy Paicu <andypaicu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#507481}