Adopt is/toHTMLFormElement for code cleanup

Adopt is/toHTMLFormElement for code cleanup
https://bugs.webkit.org/show_bug.cgi?id=117937

Reviewed by Andreas Kling.

This refers to http://src.chromium.org/viewvc/blink?view=revision&revision=152859

To enhance readibility, this patch adopts is/toHTMLFormElement.
This also helps out to reduce duplicated use of static_cast.

Source/WebCore:

* accessibility/AccessibilityRenderObject.cpp:
(WebCore::AccessibilityRenderObject::determineAccessibilityRole):
* bindings/js/JSDOMFormDataCustom.cpp:
(WebCore::toHTMLFormElement):
* bindings/js/JSHTMLFormElementCustom.cpp:
(WebCore::JSHTMLFormElement::nameGetter):
* editing/FrameSelection.cpp:
(WebCore::scanForForm):
(WebCore::FrameSelection::currentForm):
* editing/InsertParagraphSeparatorCommand.cpp:
(WebCore::InsertParagraphSeparatorCommand::doApply):
* html/FormAssociatedElement.cpp:
(WebCore::FormAssociatedElement::findAssociatedForm):
* html/HTMLElement.cpp:
(WebCore::HTMLElement::findFormAncestor):
* html/HTMLFormControlsCollection.cpp:
(WebCore::HTMLFormControlsCollection::HTMLFormControlsCollection):
(WebCore::HTMLFormControlsCollection::formControlElements):
(WebCore::HTMLFormControlsCollection::formImageElements):
(WebCore::HTMLFormControlsCollection::updateNameCache):
* html/HTMLFormElement.h:
(WebCore::isHTMLFormElement):
(WebCore::toHTMLFormElement):
* html/HTMLImageElement.cpp:
(WebCore::HTMLImageElement::insertedInto):
* html/HTMLNameCollection.cpp:
(WebCore::WindowNameCollection::nodeMatchesIfNameAttributeMatch):
(WebCore::DocumentNameCollection::nodeMatchesIfNameAttributeMatch):
(WebCore::DocumentNameCollection::nodeMatches):
* html/RadioInputType.cpp:
(WebCore::RadioInputType::handleKeydownEvent):
* html/RadioNodeList.cpp:
(WebCore::RadioNodeList::RadioNodeList):
(WebCore::RadioNodeList::checkElementMatchesRadioNodeListFilter):
* html/parser/HTMLConstructionSite.cpp:
(WebCore::HTMLConstructionSite::insertHTMLFormElement):
* html/parser/HTMLTreeBuilder.cpp:
(WebCore::closestFormAncestor):
* page/Frame.cpp:
(WebCore::Frame::searchForLabelsBeforeElement):

Source/WebKit/blackberry:

* WebCoreSupport/CredentialManager.cpp:
(WebCore::CredentialManager::autofillPasswordForms):

Source/WebKit/win:

* DOMCoreClasses.cpp:
(DOMElement::createInstance):
* DOMHTMLClasses.cpp:
(DOMHTMLFormElement::action):
(DOMHTMLFormElement::method):
* WebFrame.cpp:
(formElementFromDOMElement):

Source/WebKit2:

* WebProcess/WebPage/WebFrame.cpp:
(WebKit::WebFrame::containsAnyFormElements):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@151949 268f45cc-cd09-0410-ab3c-d52691b4dbfc