Unprefix CSS user-select property
Parse 'user-select' in the same way as '-webkit-user-select', and make the latter
an alias of the former.
Intent to Ship:https://groups.google.com/a/chromium.org/forum/#!searchin/blink-
dev/user-select/blink-dev/2VWDU83_VzQ/Dw9l33nyAgAJ
BUG=
461018
Committed:
https://crrev.com/a664cb352ef4e15f7e02ddfe2caae2c6d243a343
Cr-Commit-Position: refs/heads/master@{#413047}