Implement a simple version of SelectorQuery.

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

Index: third_party/WebKit/Source/core/dom/query/SelectorTagMatcher.cpp
diff --git a/third_party/WebKit/Source/core/dom/query/SelectorTagMatcher.cpp b/third_party/WebKit/Source/core/dom/query/SelectorTagMatcher.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..e8b645b2d56cb0b217b8446dcaa4663c5cac0852
--- /dev/null
+++ b/third_party/WebKit/Source/core/dom/query/SelectorTagMatcher.cpp
@@ -0,0 +1,36 @@
+// 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/SelectorTagMatcher.h"
+
+#include "core/dom/ContainerNode.h"
+#include "core/dom/Element.h"
+
+namespace blink {
+
+SelectorTagMatcher::SelectorTagMatcher(const QualifiedName& tagName)
+    : m_tagName(tagName)
+{
+    ASSERT(m_tagName != anyQName());
+}
+
+SelectorTagMatcher::~SelectorTagMatcher()
+{
+}
+
+bool SelectorTagMatcher::match(Element& element, ContainerNode& rootNode) const
+{
+    if (element.hasLocalName(m_tagName.localName()))
+        return true;
+    // Non-html elements in html documents are normalized to their camel-cased
+    // version during parsing if applicable. Yet, type selectors are lower-cased
+    // for selectors in html documents. Compare the upper case converted names
+    // instead to allow matching SVG elements like foreignObject.
+    if (!element.isHTMLElement() && element.document().isHTMLDocument())
+        return element.tagQName().localNameUpper() == m_tagName.localNameUpper();
+    return false;
+}
+
+}