Spin button in input[type=number] should not ignore paddings.

Source/platform/mac/ThemeMac.mm

 /*
  * Copyright (C) 2008, 2010, 2011, 2012 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 475 matching lines @@
 {
     static const IntSize sizes[3] = { IntSize(19, 27), IntSize(15, 22), IntSize(13, 15) };
     return sizes;
 }
 
 // We don't use controlSizeForFont() for steppers because the stepper height
 // should be equal to or less than the corresponding text field height,
 static NSControlSize stepperControlSizeForFont(const FontDescription& fontDescription)
 {
     int fontSize = fontDescription.computedPixelSize();
-    if (fontSize >= 18)
+    if (fontSize >= 27)
         return NSRegularControlSize;
-    if (fontSize >= 13)
+    if (fontSize >= 22)
         return NSSmallControlSize;
     return NSMiniControlSize;
 }
 
 static void paintStepper(ControlStates states, GraphicsContext* context, const IntRect& zoomedRect, float zoomFactor, ScrollView*)
 {
     // We don't use NSStepperCell because there are no ways to draw an
     // NSStepperCell with the up button highlighted.
 
     HIThemeButtonDrawInfo drawInfo;
@@ skipping 210 matching lines @@
             break;
         case InnerSpinButtonPart:
             paintStepper(states, context, zoomedRect, zoomFactor, scrollView);
             break;
         default:
             break;
     }
 }
 
 }