Adopt is/toHTMLAnchorElement for code cleanup
https://bugs.webkit.org/show_bug.cgi?id=117973

Reviewed by Andreas Kling.

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

Source/WebCore:

* accessibility/AccessibilityNodeObject.cpp:
(WebCore::AccessibilityNodeObject::anchorElement):
* accessibility/AccessibilityRenderObject.cpp:
(WebCore::AccessibilityRenderObject::anchorElement):
(WebCore::AccessibilityRenderObject::internalLinkElement):
(WebCore::AccessibilityRenderObject::url):
(WebCore::AccessibilityRenderObject::stringValueForMSAA):
(WebCore::AccessibilityRenderObject::isLinked):
* css/CSSDefaultStyleSheets.cpp:
(WebCore::elementCanUseSimpleDefaultStyle):
* css/SelectorChecker.cpp:
(WebCore::SelectorChecker::checkOne):
* dom/Document.cpp:
(WebCore::Document::updateBaseURL):
* dom/TreeScope.cpp:
(WebCore::TreeScope::findAnchor):
* dom/VisitedLinkState.cpp:
(WebCore::linkHashForElement):
(WebCore::VisitedLinkState::determineLinkStateSlowCase):
* html/HTMLAnchorElement.h:
(WebCore::isHTMLAnchorElement):
(WebCore::toHTMLAnchorElement):
* page/DragController.cpp:
(WebCore::DragController::draggableElement):
* rendering/HitTestResult.cpp:
(WebCore::HitTestResult::absoluteLinkURL):
(WebCore::HitTestResult::isLiveLink):
* rendering/RenderObject.cpp:
(WebCore::RenderObject::getTextDecorationColors):

Source/WebKit/blackberry:

* WebKitSupport/FatFingers.cpp:
(BlackBerry::WebKit::FatFingers::isElementClickable):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@151975 268f45cc-cd09-0410-ab3c-d52691b4dbfc