[Qt][WK2] Composited and transformed links asserts in tap highlight

https://bugs.webkit.org/show_bug.cgi?id=94345

Reviewed by Jocelyn Turcotte.

Use a mapping that does not assert when hitting transforms. We still skip
transforms that produces non-rectangular areas.

* page/GestureTapHighlighter.cpp:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@153893 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Task-number: QTBUG-32454
Change-Id: I608ed624047dd850c5809cdbbc688ca718add736
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>