diff --git a/gfx/2d/Types.h b/gfx/2d/Types.h
index 6fb9d955db..e3ccf2a442 100644
--- a/gfx/2d/Types.h
+++ b/gfx/2d/Types.h
@@ -406,6 +406,35 @@ static inline Side& operator++(Side& side) {
   return side;
 }
 
+namespace css {
+enum Corner {
+  // This order is important!
+  eCornerTopLeft = 0,
+  eCornerTopRight = 1,
+  eCornerBottomRight = 2,
+  eCornerBottomLeft = 3,
+  eNumCorners = 4
+};
+} // namespace css
+
+#define NS_CORNER_TOP_LEFT mozilla::css::eCornerTopLeft
+#define NS_CORNER_TOP_RIGHT mozilla::css::eCornerTopRight
+#define NS_CORNER_BOTTOM_RIGHT mozilla::css::eCornerBottomRight
+#define NS_CORNER_BOTTOM_LEFT mozilla::css::eCornerBottomLeft
+#define NS_NUM_CORNERS mozilla::css::eNumCorners
+
+#define NS_FOR_CSS_CORNERS(var_)                       \
+  for (mozilla::css::Corner var_ = NS_CORNER_TOP_LEFT; \
+       var_ <= NS_CORNER_BOTTOM_LEFT;                  \
+       var_++)
+
+static inline mozilla::css::Corner operator++(mozilla::css::Corner& corner, int) {
+  MOZ_ASSERT(corner >= NS_CORNER_TOP_LEFT &&
+             corner < NS_NUM_CORNERS, "Out of range corner");
+  corner = mozilla::css::Corner(corner + 1);
+  return corner;
+}
+
 } // namespace mozilla
 
 #endif /* MOZILLA_GFX_TYPES_H_ */
diff --git a/gfx/thebes/gfxRect.h b/gfx/thebes/gfxRect.h
index 8804ff86b2..5e057506c6 100644
--- a/gfx/thebes/gfxRect.h
+++ b/gfx/thebes/gfxRect.h
@@ -27,36 +27,6 @@ struct gfxMargin : public mozilla::gfx::BaseMargin<gfxFloat, gfxMargin> {
     : Super(aTop, aRight, aBottom, aLeft) {}
 };
 
-namespace mozilla {
-    namespace css {
-        enum Corner {
-            // this order is important!
-            eCornerTopLeft = 0,
-            eCornerTopRight = 1,
-            eCornerBottomRight = 2,
-            eCornerBottomLeft = 3,
-            eNumCorners = 4
-        };
-    } // namespace css
-} // namespace mozilla
-#define NS_CORNER_TOP_LEFT mozilla::css::eCornerTopLeft
-#define NS_CORNER_TOP_RIGHT mozilla::css::eCornerTopRight
-#define NS_CORNER_BOTTOM_RIGHT mozilla::css::eCornerBottomRight
-#define NS_CORNER_BOTTOM_LEFT mozilla::css::eCornerBottomLeft
-#define NS_NUM_CORNERS mozilla::css::eNumCorners
-
-#define NS_FOR_CSS_CORNERS(var_)                         \
-    for (mozilla::css::Corner var_ = NS_CORNER_TOP_LEFT; \
-         var_ <= NS_CORNER_BOTTOM_LEFT;                  \
-         var_++)
-
-static inline mozilla::css::Corner operator++(mozilla::css::Corner& corner, int) {
-    NS_PRECONDITION(corner >= NS_CORNER_TOP_LEFT &&
-                    corner < NS_NUM_CORNERS, "Out of range corner");
-    corner = mozilla::css::Corner(corner + 1);
-    return corner;
-}
-
 struct gfxRect :
     public mozilla::gfx::BaseRect<gfxFloat, gfxRect, gfxPoint, gfxSize, gfxMargin> {
     typedef mozilla::gfx::BaseRect<gfxFloat, gfxRect, gfxPoint, gfxSize, gfxMargin> Super;