Merge 149838 "Reland "Clear highlight when the highlighted node ..."

Merge 149838 "Reland "Clear highlight when the highlighted node ..."

> Reland "Clear highlight when the highlighted node gets removed from the document"
> 
> Some web pages use a mask element to intercept tap gesture and then hide
> the element immediately. The orphaned highlight can be very annoying.
> For example, pages that show a popup often use a full screen transparent
> element to intercept events, and will hide the popup if the user attempt
> to tap on the main document. If we don't remove highlight from the hidden
> element, the whole screen will be covered by a highlight.
> 
> This patch clears highlight from a layer when the tap node is no longer valid.
> 
> TEST=webkit_unit_tests:LinkHighlightTest.resetDuringNodeRemoval
> BUG=232926
> R=jamesr@chromium.org
> 
> Originally reviewed in https://chromiumcodereview.appspot.com/14582012
> Later reverted in https://codereview.chromium.org/14921004/
> The test failure was due to failing to unregister mocked URLs after test.
> 
> Review URL: https://chromiumcodereview.appspot.com/14729006

TBR=trchen@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=151511

[trchen, 2013-05-31 02:06:12]

Committed patchset #1 manually as r151511.