Let StyleResolver figure out differences between UA style and resolved style.

Source/core/layout/LayoutTheme.h

Index: Source/core/layout/LayoutTheme.h
diff --git a/Source/core/layout/LayoutTheme.h b/Source/core/layout/LayoutTheme.h
index 61b01dc15c48a5737b08d3770102509f220da262..9c5cc68d918523a33210b04f95a10969fde61885 100644
--- a/Source/core/layout/LayoutTheme.h
+++ b/Source/core/layout/LayoutTheme.h
@@ -29,7 +29,6 @@
 #include "platform/ThemeTypes.h"
 #endif
 #include "core/rendering/RenderObject.h"
-#include "core/rendering/style/CachedUAStyle.h"
 #include "platform/scroll/ScrollTypes.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
@@ -42,6 +41,7 @@ class FileList;
 class HTMLInputElement;
 class RenderMeter;
 class RenderProgress;
+class UAStyleChange;
 
 
 class LayoutTheme : public RefCounted<LayoutTheme> {
@@ -62,7 +62,7 @@ public:
     // metrics and defaults given the contents of the style.  This includes sophisticated operations like
     // selection of control size based off the font, the disabling of appearance when certain other properties like
     // "border" are set, or if the appearance is not supported by the theme.
-    void adjustStyle(RenderStyle*, Element*, const CachedUAStyle*);
+    void adjustStyle(RenderStyle*, Element*, const UAStyleChange&);
 
     // This method is called to paint the widget as a background of the RenderObject.  A widget's foreground, e.g., the
     // text of a button, is always rendered by the engine itself.  The boolean return value indicates
@@ -91,7 +91,7 @@ public:
     bool isControlContainer(ControlPart) const;
 
     // Whether or not the control has been styled enough by the author to disable the native appearance.
-    virtual bool isControlStyled(const RenderStyle*, const CachedUAStyle*) const;
+    virtual bool isControlStyled(const RenderStyle*, const UAStyleChange&) const;
 
     // Some controls may spill out of their containers (e.g., the check on an OS X checkbox). When these controls issues paint invalidations,
     // the theme needs to communicate this inflated rect to the engine so that it can invalidate the whole control.