Mac: Fallback to CSS rendering if buttons has non-100% scale.

Source/core/layout/LayoutThemeMac.mm

 /*
  * Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Google, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 440 matching lines @@
         return style.hasAuthorBorder() || style.boxShadow();
 
     // FIXME: This is horrible, but there is not much else that can be done.
     // Menu lists cannot draw properly when scaled. They can't really draw
     // properly when transformed either. We can't detect the transform case at
     // style adjustment time so that will just have to stay broken.  We can
     // however detect that we're zooming. If zooming is in effect we treat it
     // like the control is styled.
     if (style.appearance() == MenulistPart && style.effectiveZoom() != 1.0f)
         return true;
-    // FIXME: NSSearchFieldCell doesn't work well when scaled.
-    if (style.appearance() == SearchFieldPart && style.effectiveZoom() != 1)
-        return true;
-
+    // Some other cells don't work well when scaled.
+    if (style.effectiveZoom() != 1) {
+        switch (style.appearance()) {
+        case ButtonPart:
+        case PushButtonPart:
+        case SearchFieldPart:
+        case SquareButtonPart:
+            return true;
+        default:
+            break;
+        }
+    }
     return LayoutTheme::isControlStyled(style);
 }
 
 void LayoutThemeMac::addVisualOverflow(const LayoutObject& object, IntRect& rect)
 {
     ControlPart part = object.style()->appearance();
 
 #if USE(NEW_THEME)
     switch (part) {
     case CheckboxPart:
@@ skipping 690 matching lines @@
 
 bool LayoutThemeMac::shouldUseFallbackTheme(const ComputedStyle& style) const
 {
     ControlPart part = style.appearance();
     if (part == CheckboxPart || part == RadioPart)
         return style.effectiveZoom() != 1;
     return false;
 }
 
 } // namespace blink