[CSS Typed OM] Rearrange StylePropertyMap classes to match the new spec.

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
index 49d044a0549f18a634b2d839a477f543db393b49..6d9aab5c0cf6c04c4d038d70762ff5ec5dbfb92b 100644
--- a/third_party/WebKit/Source/core/css/cssom/WindowGetComputedStyle.h
+++ b/third_party/WebKit/Source/core/css/cssom/WindowGetComputedStyle.h
@@ -14,9 +14,10 @@ class WindowGetComputedStyle {
   STATIC_ONLY(WindowGetComputedStyle);
 
  public:
-  static StylePropertyMap* getComputedStyleMap(const LocalDOMWindow&,
-                                               Element* element,
-                                               const String& pseudoElement) {
+  static StylePropertyMapReadonly* getComputedStyleMap(
+      const LocalDOMWindow&,
+      Element* element,
+      const String& pseudoElement) {
     DCHECK(element);
     return ComputedStylePropertyMap::create(element, pseudoElement);
   }