Implement ComputedStylePropertyMap for Typed OM.

third_party/WebKit/Source/core/css/cssom/WindowGetComputedStyle.h

Index: third_party/WebKit/Source/core/css/cssom/WindowGetComputedStyle.h
diff --git a/third_party/WebKit/Source/core/css/cssom/WindowGetComputedStyle.h b/third_party/WebKit/Source/core/css/cssom/WindowGetComputedStyle.h
new file mode 100644
index 0000000000000000000000000000000000000000..7ca300278ac23fc02a0ed6d269633dea3a54bbe9
--- /dev/null
+++ b/third_party/WebKit/Source/core/css/cssom/WindowGetComputedStyle.h
@@ -0,0 +1,28 @@
+// Copyright 2016 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 WindowGetComputedStyle_h
+#define WindowGetComputedStyle_h
+
+#include "core/css/CSSComputedStyleDeclaration.h"
+#include "core/css/cssom/ComputedStylePropertyMap.h"
+#include "core/dom/Document.h"
+#include "wtf/Allocator.h"
+
+namespace blink {
+
+class WindowGetComputedStyle {
+    STATIC_ONLY(WindowGetComputedStyle);
+public:
+    static StylePropertyMap* getComputedStyleMap(const DOMWindow&, Element* elt, const String& pseudoElt)
+    {
+        ASSERT(elt);

[Timothy Loh, 2016/03/31 06:59:25]

Not sure about this, what happens if you use null? We should test that. Also
please don't use abbreviated names in Blink, just write element and
pseudoElement.

[meade_UTC10, 2016/04/04 03:32:41]

Done. FWIW, this was pretty much copied from here:
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

In this case (and the linked one) the generated code type checks that the
Element argument is actually an argument and throws a JS exception, so it
shouldn't get here if element is null.

+        RefPtrWillBeRawPtr<CSSComputedStyleDeclaration> computedStyleDeclaration = CSSComputedStyleDeclaration::create(elt, false, pseudoElt);
+        return ComputedStylePropertyMap::create(computedStyleDeclaration);
+    }
+};
+
+} // namespace blink
+
+#endif // WindowGetComputedStyle_h