Move Node::supportsFocus() to Element.
<http://webkit.org/b/116778>

Reviewed by Antti Koivisto.

Node never supports focus, so move supportsFocus() to Element instead.

* dom/Element.h:
* dom/Node.cpp:
* dom/Node.h:

    Removed Node::supportsFocus(), it always returned false anyway.

* accessibility/AccessibilityNodeObject.cpp:
(WebCore::AccessibilityNodeObject::canSetFocusAttribute):

    Check that the underlying Node is an Element before asking if it supports focus.

* html/HTMLAnchorElement.h:
* html/HTMLAreaElement.h:
* html/HTMLBodyElement.h:
* html/HTMLElement.h:
* html/HTMLFieldSetElement.h:
* html/HTMLFormControlElement.h:
* html/HTMLFrameElementBase.h:
* html/HTMLMediaElement.h:
* html/HTMLOptGroupElement.h:
* html/HTMLOptionElement.h:
* html/HTMLOutputElement.h:
* svg/SVGAElement.h:
* svg/SVGCircleElement.h:
* svg/SVGEllipseElement.h:
* svg/SVGGElement.h:
* svg/SVGImageElement.h:
* svg/SVGLineElement.h:
* svg/SVGPathElement.h:
* svg/SVGPolyElement.h:
* svg/SVGRectElement.h:
* svg/SVGSVGElement.h:
* svg/SVGSwitchElement.h:
* svg/SVGSymbolElement.h:
* svg/SVGTextElement.h:
* svg/SVGUseElement.h:

    OVERRIDE ALL THE THINGS!

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@150710 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Move some form control things from Element to HTMLFormControlElement.
<http://webkit.org/b/116779>

Reviewed by Antti Koivisto.

The following methods sit better on HTMLFormControlElement than on Element:

    - formControlType()
    - wasChangedSinceLastFormControlChangeEvent()
    - setChangedSinceLastFormControlChangeEvent()
    - dispatchFormControlChangeEvent()

Moved them, and devirtualized as much as possible.

* dom/Document.cpp:
(WebCore::Document::setFocusedNode):

    Check if the old focus target is an Element before (possibly) dispatching a change event.

* dom/Element.cpp:
* dom/Element.h:

    Removed some stub methods that were only used by HTMLFormControlElement subclasses.

* html/HTMLFormControlElement.cpp:
* html/HTMLFormControlElement.h:
(WebCore::isHTMLFormControlElement):
(WebCore::toHTMLFormControlElement):

    Add toHTMLFormControlElement() helper with ASSERT_WITH_SECURITY_IMPLICATION.

* html/HTMLTextFormControlElement.h:

    Sprinkle OVERRIDE.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@150711 268f45cc-cd09-0410-ab3c-d52691b4dbfc