Add lots more tests for SelectorQuery fast paths.

third_party/WebKit/Source/core/dom/SelectorQuery.cpp

 /*
  * Copyright (C) 2011, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Samsung Electronics. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 251 matching lines @@
         return;
       }
       // Since there exists some ancestor element which has the class name, we
       // need to see all children of rootNode.
       if (AncestorHasClassName(root_node, selector->Value()))
         break;
 
       const AtomicString& class_name = selector->Value();
       Element* element = ElementTraversal::FirstWithin(root_node);
       while (element) {
+        QUERY_STATS_INCREMENT(fast_class);
         if (HasClassName(*element, class_name)) {
           ExecuteForTraverseRoot<SelectorQueryTrait>(*element, root_node,
                                                      output);
           element =
               ElementTraversal::NextSkippingChildren(*element, &root_node);
         } else {
           element = ElementTraversal::Next(*element, &root_node);
         }
       }
       return;
@@ skipping 268 matching lines @@
   return entries_
       .insert(selectors, SelectorQuery::Adopt(std::move(selector_list)))
       .stored_value->value.get();
 }
 
 void SelectorQueryCache::Invalidate() {
   entries_.Clear();
 }
 
 }  // namespace blink