Support multiple text decoration styles.

Source/core/rendering/RenderObject.h

Index: Source/core/rendering/RenderObject.h
diff --git a/Source/core/rendering/RenderObject.h b/Source/core/rendering/RenderObject.h
index 4c8d0ded7497b86946f39257326fce89306cf8ee..bd2ab962faf2f113d7a38f756583c284cdcdce20 100644
--- a/Source/core/rendering/RenderObject.h
+++ b/Source/core/rendering/RenderObject.h
@@ -783,7 +783,13 @@ public:
 
     virtual CursorDirective getCursor(const LayoutPoint&, Cursor&) const;
 
-    void getTextDecorationColors(unsigned decorations, Color& underline, Color& overline, Color& linethrough, bool quirksMode = false, bool firstlineStyle = false);
+    struct AppliedTextDecoration {
+        Color color;
+        TextDecorationStyle style;
+        AppliedTextDecoration() : color(Color::transparent), style(TextDecorationStyleSolid) { }
+    };
+
+    void getTextDecorations(unsigned decorations, AppliedTextDecoration& underline, AppliedTextDecoration& overline, AppliedTextDecoration& linethrough, bool quirksMode = false, bool firstlineStyle = false);
 
     // Return the RenderLayerModelObject in the container chain which is responsible for painting this object, or 0
     // if painting is root-relative. This is the container that should be passed to the 'forRepaint'