Inserting nodes is slow due to Node::notifyNodeListsAttributeChanged (20%+)

Inserting nodes is slow due to Node::notifyNodeListsAttributeChanged (20%+)
https://bugs.webkit.org/show_bug.cgi?id=73853

Reviewed by Antti Koivisto.

Lazily invalidate the node list caches instead of invaliding them at the time of modification. We use
the DOM tree version to detect whether caches need to be invalidated or not. We now invalidate caches more
frequently after this patch (in particular, invalidates caches that are stored on nodes not present in
the ancestry of the modified nodes); however, our study on major Web sites such as Gmail, Facebook, Twitter,
etc... indicate that about 1% of real-world usage benefits from keeping the caches alive across different
DOM tree versions.

In order to invalidate caches lazily, this patch adds replaces the type of m_caches in DynamicSubtreeNodeList
by DynamicSubtreeNodeList::SubtreeCaches which encapsulates member variables in DynamicNodeList::Caches and
invalidates values as needed. Also this change allows m_caches to be allocated as a part of
DynamicSubtreeNodeList instead of a separate ref-counted object.

* dom/Attr.cpp:
(WebCore::Attr::setValue):
(WebCore::Attr::childrenChanged):
* dom/DynamicNodeList.cpp:
(WebCore::DynamicSubtreeNodeList::DynamicSubtreeNodeList):
(WebCore::DynamicSubtreeNodeList::length):
(WebCore::DynamicSubtreeNodeList::itemForwardsFromCurrent):
(WebCore::DynamicSubtreeNodeList::itemBackwardsFromCurrent):
(WebCore::DynamicSubtreeNodeList::item):
(WebCore::DynamicSubtreeNodeList::invalidateCache):
(WebCore::DynamicNodeList::Caches::create):
(WebCore::DynamicNodeList::Caches::reset):
* dom/DynamicNodeList.h:
(WebCore::DynamicSubtreeNodeList::SubtreeCaches::SubtreeCaches): Added.
(WebCore::DynamicSubtreeNodeList::SubtreeCaches::isLengthCacheValid): Added.
(WebCore::DynamicSubtreeNodeList::SubtreeCaches::isItemCacheValid): Added.
(WebCore::DynamicSubtreeNodeList::SubtreeCaches::cachedLength): Added.
(WebCore::DynamicSubtreeNodeList::SubtreeCaches::cachedItem): Added.
(WebCore::DynamicSubtreeNodeList::SubtreeCaches::cachedItemOffset): Added.
(WebCore::DynamicSubtreeNodeList::SubtreeCaches::setLengthCache): Added.
(WebCore::DynamicSubtreeNodeList::SubtreeCaches::setItemCache): Added.
(WebCore::DynamicSubtreeNodeList::SubtreeCaches::reset): Added.
(WebCore::DynamicSubtreeNodeList::SubtreeCaches::domVersionIsConsistent): Added.
* dom/Element.cpp:
(WebCore::Element::updateAfterAttributeChanged):
* dom/Node.cpp:
(WebCore::Node::setTreeScopeRecursively): Clear caches when a node moves from one document to another.
(WebCore::Node::invalidateNodeListsCacheAfterAttributeChanged): Only clears child node list of Attr.
(WebCore::Node::invalidateNodeListsCacheAfterChildrenChanged): Only clears child node list.
(WebCore::NodeListsNodeData::invalidateCaches): Merged with invalidateCachesThatDependOnAttributes.
* dom/Node.h:
* dom/NodeRareData.h:
* html/HTMLElement.cpp:
(WebCore::HTMLElement::parseMappedAttribute):
* html/HTMLLabelElement.cpp:
* html/HTMLLabelElement.h:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@104084 268f45cc-cd09-0410-ab3c-d52691b4dbfc