Implement a simple version of SelectorQuery.

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

Index: third_party/WebKit/Source/core/dom/query/SelectorMatcher.cpp
diff --git a/third_party/WebKit/Source/core/dom/query/SelectorMatcher.cpp b/third_party/WebKit/Source/core/dom/query/SelectorMatcher.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..2b3a3ef7f006b6bd4dd444c56600040ff8503b4a
--- /dev/null
+++ b/third_party/WebKit/Source/core/dom/query/SelectorMatcher.cpp
@@ -0,0 +1,35 @@
+// 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.
+
+#include "config.h"
+#include "core/dom/query/SelectorMatcher.h"
+
+#include "core/dom/ContainerNode.h"
+#include "core/dom/Element.h"
+#include "core/dom/ElementTraversal.h"
+
+namespace blink {
+
+SelectorMatcher::~SelectorMatcher()
+{
+}
+
+Element* SelectorMatcher::findFirst(ContainerNode& rootNode) const
+{
+    for (Element& element : ElementTraversal::descendantsOf(rootNode)) {
+        if (match(element, rootNode))
+            return &element;
+    }
+    return nullptr;
+}
+
+void SelectorMatcher::findAll(ContainerNode& rootNode, WillBeHeapVector<RefPtrWillBeMember<Element>>& result) const
+{
+    for (Element& element : ElementTraversal::descendantsOf(rootNode)) {
+        if (match(element, rootNode))
+            result.append(&element);
+    }
+}
+
+}