Implement a simple version of SelectorQuery.

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

Index: third_party/WebKit/Source/core/dom/query/SelectorIdMatcher.cpp
diff --git a/third_party/WebKit/Source/core/dom/query/SelectorIdMatcher.cpp b/third_party/WebKit/Source/core/dom/query/SelectorIdMatcher.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..ff0e9ca01b9a08e275ab50074208d88534773dd1
--- /dev/null
+++ b/third_party/WebKit/Source/core/dom/query/SelectorIdMatcher.cpp
@@ -0,0 +1,56 @@
+// 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/SelectorIdMatcher.h"
+
+#include "core/dom/ContainerNode.h"
+#include "core/dom/Element.h"
+
+namespace blink {
+
+SelectorIdMatcher::SelectorIdMatcher(const AtomicString& id)
+    : m_id(id)
+{
+}
+
+SelectorIdMatcher::~SelectorIdMatcher()
+{
+}
+
+Element* SelectorIdMatcher::findFirst(ContainerNode& rootNode) const
+{
+    if (!rootNode.isInTreeScope() || rootNode.document().inQuirksMode())
+        return SelectorMatcher::findFirst(rootNode);
+    Element* element = rootNode.treeScope().getElementById(m_id);
+    if (element && element->isDescendantOf(&rootNode))
+        return element;
+    return nullptr;
+}
+
+void SelectorIdMatcher::findAll(ContainerNode& rootNode, WillBeHeapVector<RefPtrWillBeMember<Element>>& result) const
+{
+    if (!rootNode.isInTreeScope() || rootNode.document().inQuirksMode()) {
+        SelectorMatcher::findAll(rootNode, result);
+        return;
+    }
+    if (rootNode.treeScope().containsMultipleElementsWithId(m_id)) {
+        const auto& elements = rootNode.treeScope().getAllElementsById(m_id);
+        for (auto& element : elements) {
+            if (element->isDescendantOf(&rootNode))
+                result.append(element);
+        }
+        return;
+    }
+    Element* element = rootNode.treeScope().getElementById(m_id);
+    if (element && element->isDescendantOf(&rootNode))
+        result.append(element);
+}
+
+bool SelectorIdMatcher::match(Element& element, ContainerNode& rootNode) const
+{
+    return element.hasID() && element.idForStyleResolution() == m_id;
+}
+
+}