Crash when right clicking in input box with -webkit-user-select: none

Crash when right clicking in input box with -webkit-user-select: none
https://bugs.webkit.org/show_bug.cgi?id=145981
<rdar://problem/22441925>

Reviewed by Enrica Casucci.

Source/WebCore:

Test: editing/selection/minimal-user-select-crash.html

* editing/Editor.cpp:
(WebCore::Editor::hasBidiSelection):
Visible position cannot be created because of the style that doesn't allow the selection.

LayoutTests:

* editing/selection/minimal-user-select-crash-expected.txt: Added.
* editing/selection/minimal-user-select-crash.html: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@192191 268f45cc-cd09-0410-ab3c-d52691b4dbfc