[NotLanded] Implement the fetching algorithm of the Web Manifest.

Source/web/WebNodeTest.cpp

 // Copyright 2014 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 "public/web/WebNode.h"
 
+#include "core/dom/Document.h"
+#include "core/dom/Element.h"
 #include "core/testing/DummyPageHolder.h"
 #include "public/web/WebElement.h"
 #include "public/web/WebElementCollection.h"
 #include <gtest/gtest.h>
 
 namespace blink {
 
 class WebNodeTest : public testing::Test {
 protected:
     Document& document() { return m_pageHolder->document(); }
@@ skipping 16 matching lines @@
     // WebNode::getElementsByHTMLTagName returns only HTML elements.
     WebElementCollection collection = node.getElementsByHTMLTagName("label");
     EXPECT_EQ(1u, collection.length());
     EXPECT_TRUE(collection.firstItem().hasHTMLTagName("label"));
     // The argument should be lower-case.
     collection = node.getElementsByHTMLTagName("LABEL");
     EXPECT_EQ(0u, collection.length());
 }
 
 }