Support getComputedStyle for non-rendered pseudo elements.

Source/core/css/PseudoStyleRequest.h

Index: Source/core/css/PseudoStyleRequest.h
diff --git a/Source/core/css/PseudoStyleRequest.h b/Source/core/css/PseudoStyleRequest.h
index 7347ef393350486e88c47f0ba76cd6d088317fb6..049397f01134d16e63c934975c016bde66881225 100644
--- a/Source/core/css/PseudoStyleRequest.h
+++ b/Source/core/css/PseudoStyleRequest.h
@@ -32,13 +32,25 @@ class RenderStyle;
 
 class PseudoStyleRequest {
 public:
+
+    enum RequestType { ForRenderer, ForComputedStyle };
+
     PseudoStyleRequest(PseudoId pseudoId, RenderScrollbar* scrollbar = 0, ScrollbarPart scrollbarPart = NoPart)
         : pseudoId(pseudoId)
+        , type(ForRenderer)
         , scrollbarPart(scrollbarPart)
         , scrollbar(scrollbar)
     {
     }
 
+    PseudoStyleRequest(PseudoId pseudoId, RequestType requestType)
+        : pseudoId(pseudoId)
+        , type(requestType)
+        , scrollbarPart(NoPart)
+        , scrollbar(0)
+    {
+    }
+
     // The spec disallows inheritance for ::backdrop.
     bool allowsInheritance(const RenderStyle* parentStyle) const
     {
@@ -46,6 +58,7 @@ public:
     }
 
     PseudoId pseudoId;
+    RequestType type;
     ScrollbarPart scrollbarPart;
     RenderScrollbar* scrollbar;
 };