Do not cause unnecessary node lists invalidation on id/name attribute change

Source/core/dom/Document.h

Index: Source/core/dom/Document.h
diff --git a/Source/core/dom/Document.h b/Source/core/dom/Document.h
index 4fa870bdcf8ccd59138f293e85766194fe2c40c7..d2c5d8c8e68a1bb9e646363b459eff6d41f3f829 100644
--- a/Source/core/dom/Document.h
+++ b/Source/core/dom/Document.h
@@ -650,6 +650,8 @@ public:
 
     void registerNodeList(LiveNodeListBase*);
     void unregisterNodeList(LiveNodeListBase*);
+    void incrementNodeListWithIdNameCacheCount();
+    void decrementNodeListWithIdNameCacheCount();
     bool shouldInvalidateNodeListCaches(const QualifiedName* attrName = 0) const;
     void invalidateNodeListCaches(const QualifiedName* attrName);
 
@@ -1377,6 +1379,17 @@ inline bool Document::shouldOverrideLegacyDescription(ViewportDescription::Type
     return origin >= m_legacyViewportDescription.type;
 }
 
+inline void Document::incrementNodeListWithIdNameCacheCount()
+{
+    m_nodeListCounts[InvalidateOnIdNameAttrChange]++;

[eseidel, 2014/02/12 01:55:24]

This seems about the same size as just keeping a list of the pointers.  I wonder
what the tradeoff would be there.

[Inactive, 2014/02/12 02:21:41]

You mean an array of linked lists (whose items would be LiveNodeListBase
pointers) instead of an array of integers? My worry is that this could grow to
use quite a bit more memory if we have more than one LiveNodeListBase per
invalidation type.

+}
+
+inline void Document::decrementNodeListWithIdNameCacheCount()
+{
+    ASSERT(m_nodeListCounts[InvalidateOnIdNameAttrChange] > 0);

[Inactive, 2014/02/12 02:21:41]

You mentioned having good assertions an IRC. There is this one to make sure we
don't decrement more than we should.

And there is a pre-existing assertion in the Document destructor to make sure we
decrement enough (i.e. No list is still registered when the document is
destroyed):
for (unsigned i = 0; i < WTF_ARRAY_LENGTH(m_nodeListCounts); i++)
        ASSERT(!m_nodeListCounts[i]);

+    m_nodeListCounts[InvalidateOnIdNameAttrChange]--;
+}
+
 DEFINE_TYPE_CASTS(Document, ExecutionContextClient, client, client->isDocument(), client.isDocument());
 DEFINE_TYPE_CASTS(Document, ExecutionContext, context, context->isDocument(), context.isDocument());
 DEFINE_NODE_TYPE_CASTS(Document, isDocumentNode());