Avoid copying the CachedUAStyle when possible

Source/core/rendering/style/CachedUAStyle.h

Index: Source/core/rendering/style/CachedUAStyle.h
diff --git a/Source/core/rendering/style/CachedUAStyle.h b/Source/core/rendering/style/CachedUAStyle.h
index 2b98e5159f26e5ee115ae470b57aad7e716c1d86..a3d7446128baca8992dc2d1fc2cd0fdd82991402 100644
--- a/Source/core/rendering/style/CachedUAStyle.h
+++ b/Source/core/rendering/style/CachedUAStyle.h
@@ -39,15 +39,11 @@ public:
     { }
 
     explicit CachedUAStyle(const RenderStyle* style)
-        : hasAppearance(style->hasAppearance())
+        : hasAppearance(true)
         , backgroundLayers(BackgroundFillLayer)
         , backgroundColor(StyleColor::currentColor())
     {
-        // RenderTheme::adjustStyle is the only consumer of this data.
-        // It only cares about the styles if appearance is set,
-        // so we cheat and don't bother to copy them when !hasAppearance.
-        if (!hasAppearance)
-            return;
+        ASSERT(style->hasAppearance());
         border = style->border();
         backgroundLayers = *style->backgroundLayers();
         backgroundColor = style->backgroundColor();