https://bugs.webkit.org/show_bug.cgi?id=113270

Reviewed by Enrica Casucci.

Source/WebCore:

The bug was caused by updateSelectionForMouseDownDispatchingSelectStart always replacing selection whenever
the target node was inside an element with -webkit-suer-select even when we were attemping to extend selection
in handleMousePressEventSingleClick.

Fixed the bug by extracting this logic as a separate function (expandSelectionToRespectUserSelectAll) and deploying
it in handleMousePressEventSingleClick to extend selection as needed.

Test: editing/selection/user-select-all-with-shift.html

* page/EventHandler.cpp:
(WebCore::expandSelectionToRespectUserSelectAll): Extracted from updateSelectionForMouseDownDispatchingSelectStart.
(WebCore::EventHandler::updateSelectionForMouseDownDispatchingSelectStart):
(WebCore::EventHandler::selectClosestWordFromHitTestResult):
(WebCore::EventHandler::selectClosestWordOrLinkFromMouseEvent):
(WebCore::EventHandler::handleMousePressEventTripleClick):
(WebCore::EventHandler::handleMousePressEventSingleClick): Adjust "pos" as needed when extending selection.
Also use shouldConsiderSelectionAsDirectional() instead of manually peeking editingBehaviorType while we're at it.

LayoutTests:

Added a regression test for shift clicking on an element with -webkit-user-select: all.
Skip it on non-Mac platforms as -webkit-user-select: all hasn't been enabled on them.

* editing/selection/user-select-all-with-shift-expected.txt: Added.
* editing/selection/user-select-all-with-shift.html: Added.
* platform/chromium/TestExpectations:
* platform/efl/TestExpectations:
* platform/gtk/TestExpectations:
* platform/qt/TestExpectations:
* platform/win/TestExpectations:
* platform/wincairo/TestExpectations:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@147022 268f45cc-cd09-0410-ab3c-d52691b4dbfc