Make BleedingEdgeFastPaths imply will-change 

This enables the CSSWillChange RuntimeEnabledFeature when the
BleedingEdgeFastPaths WebRuntimeFeature is enabled.

BUG=313532

Review URL: https://codereview.chromium.org/197463002

git-svn-id: svn://svn.chromium.org/blink/trunk@169077 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Expose the selection root bounds in WebView.

This will allow consumers to decide whether they want to UI related to
selection such as selection handlers in touch devices.

BUG=236033

Review URL: https://codereview.chromium.org/177903010

git-svn-id: svn://svn.chromium.org/blink/trunk@169078 bbb929c8-8fbe-4397-9dbb-9b2b20218538