[Qt] Unreviewed gardening. Rebase tests.

Patch by Gabor Abraham <abrhm@inf.u-szeged.hu> on 2013-09-20

* platform/qt-wk2/fast/css/word-space-extra-expected.png: Added r155957.
* platform/qt/fast/css/pseudo-first-line-border-width-expected.png: Rebase after r155957.
* platform/qt/fast/css/pseudo-first-line-border-width-expected.txt: Rebase after r155957.
* platform/qt/fast/css/word-space-extra-expected.txt: Rebase after r155957.
* platform/qt/fast/forms/select-empty-option-height-expected.txt: Rebase after rr156040.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@156143 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Add covariant RenderElement* Element::renderer()
https://bugs.webkit.org/show_bug.cgi?id=121638

Reviewed by Andreas Kling.

Also add isRenderElement() test and casting functions.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@156144 268f45cc-cd09-0410-ab3c-d52691b4dbfc