[chromium] WebViewImpl::enableTouchHighlight() should always clear any existing highlight when invoked.
https://bugs.webkit.org/show_bug.cgi?id=94978

Reviewed by James Robinson.

Modified WebViewImpl::enableTouchHighlight() so it always clears any existing highlight, even if no new
highlight target is found.

Source/WebKit/chromium:

* src/WebViewImpl.cpp:
(WebKit::WebViewImpl::enableTouchHighlight):

LayoutTests:

* platform/chromium-linux/compositing/gestures/gesture-tapHighlight-simple-cancel.html: Added.
* platform/chromium-linux/platform/chromium-linux/compositing/gestures/gesture-tapHighlight-simple-cancel-expected.png: Added.
* platform/chromium-linux/platform/chromium-linux/compositing/gestures/gesture-tapHighlight-simple-cancel-expected.txt: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@126654 268f45cc-cd09-0410-ab3c-d52691b4dbfc