Add ElementAttributeData class to replace internal uses of NamedNodeMap

Add ElementAttributeData class to replace internal uses of NamedNodeMap
https://bugs.webkit.org/show_bug.cgi?id=77233

Reviewed by Andreas Kling.

Move part of non-DOM functionality of NamedNodeMap into a separate class. This is
the first step toward the goal of separating NamedNodeMap from internal attribute
storage, as described in https://bugs.webkit.org/show_bug.cgi?id=75069.

The internal attribute storage is exposed as attributeData() in Element, and when
necessary (because it has no back pointer to Element) via methods in Element.

No new tests. Except from setClass() change this is just moving the code, no new
feature was added.

* CMakeLists.txt:
* GNUmakefile.list.am:
* Target.pri:
* WebCore.gypi:
* WebCore.xcodeproj/project.pbxproj:
* dom/DOMAllInOne.cpp:
* dom/Element.cpp:
(WebCore::Element::idAttributeChanged):
* dom/Element.h:
(WebCore::Element::attributeData):
(WebCore::Element::ensureAttributeData):
(Element):
(WebCore::Element::idForStyleResolution):
* dom/ElementAttributeData.cpp: Added.
(WebCore):
(WebCore::ElementAttributeData::setClass): the only caller of this function
already deal with the case when the element has no class, so don't do it here.
* dom/ElementAttributeData.h: Added.
(WebCore):
(ElementAttributeData):
(WebCore::ElementAttributeData::clearClass):
(WebCore::ElementAttributeData::classNames):
(WebCore::ElementAttributeData::idForStyleResolution):
(WebCore::ElementAttributeData::setIdForStyleResolution):
(WebCore::ElementAttributeData::ElementAttributeData):
* dom/NamedNodeMap.cpp:
(WebCore::NamedNodeMap::clearAttributes):
* dom/NamedNodeMap.h:
(WebCore::NamedNodeMap::attributeData):
(NamedNodeMap):
* dom/StyledElement.cpp:
(WebCore::StyledElement::classAttributeChanged):
* dom/StyledElement.h:
(WebCore::StyledElement::classNames):
* html/ClassList.cpp:
(WebCore::ClassList::classNames):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@106323 268f45cc-cd09-0410-ab3c-d52691b4dbfc