Implement a simple version of SelectorQuery.

third_party/WebKit/Source/core/dom/query/SelectorMatcher.h

Index: third_party/WebKit/Source/core/dom/query/SelectorMatcher.h
diff --git a/third_party/WebKit/Source/core/dom/query/SelectorMatcher.h b/third_party/WebKit/Source/core/dom/query/SelectorMatcher.h
new file mode 100644
index 0000000000000000000000000000000000000000..a6fea30ae5754f28e7db4149f3cf4c3f4e717ddb
--- /dev/null
+++ b/third_party/WebKit/Source/core/dom/query/SelectorMatcher.h
@@ -0,0 +1,25 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SelectorMatcher_h
+#define SelectorMatcher_h
+
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+class ContainerNode;
+class Element;
+
+class SelectorMatcher {
+public:
+    virtual ~SelectorMatcher();
+    virtual Element* findFirst(ContainerNode& rootNode) const;
+    virtual void findAll(ContainerNode& rootNode, WillBeHeapVector<RefPtrWillBeMember<Element>>& result) const;
+    virtual bool match(Element&, ContainerNode& rootNode) const = 0;
+};
+
+}
+
+#endif