Remove TextFieldDecoration feature
https://bugs.webkit.org/show_bug.cgi?id=115068

Reviewed by Andreas Kling.

Only Chromium port used this feature.

* dom/Element.h: Remove isTextFieldDecoration.
* html/InputType.cpp:
(WebCore::InputType::destroyShadowSubtree):
Update a comment.
* html/TextFieldInputType.cpp:
(WebCore::TextFieldInputType::createShadowSubtree):
Remove call sites of willAddTextFieldDecorationsTo and addTextFieldDecorationsTo.
* html/shadow/TextFieldDecorationElement.cpp: Removed.
* html/shadow/TextFieldDecorationElement.h: Removed.
* page/ChromeClient.h:
(ChromeClient): Remove willAddTextFieldDecorationsTo and
addTextFieldDecorationsTo


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149015 268f45cc-cd09-0410-ab3c-d52691b4dbfc