Computed style of resource references drops hash from fragment

Computed style of resource references drops hash from fragment, include it when returning the computed property value for start-marker, mid-marker, end-marker, filter, mask and clip-path.
Also add a test.

BUG=232904

Review URL: https://codereview.chromium.org/302553002

git-svn-id: svn://svn.chromium.org/blink/trunk@174910 bbb929c8-8fbe-4397-9dbb-9b2b20218538