Backport WebKit patch to fix input button 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 641 matching lines @@
 LengthBox ThemeMac::controlPadding(ControlPart part, const FontDescription& fontDescription, const LengthBox& zoomedBox, float zoomFactor) const
 {
     switch (part) {
         case PushButtonPart: {
             // Just use 8px.  AppKit wants to use 11px for mini buttons, but that padding is just too large
             // for real-world Web sites (creating a huge necessary minimum width for buttons whose space is
             // by definition constrained, since we select mini only for small cramped environments.
             // This also guarantees the HTML <button> will match our rendering by default, since we're using a consistent
             // padding.
             const int padding = 8 * zoomFactor;
-            return LengthBox(0, padding, 0, padding);
+            return LengthBox(2, padding, 3, padding);
         }
         default:
             return Theme::controlPadding(part, fontDescription, zoomedBox, zoomFactor);
     }
 }
 
 void ThemeMac::inflateControlPaintRect(ControlPart part, ControlStates states, IntRect& zoomedRect, float zoomFactor) const
 {
     BEGIN_BLOCK_OBJC_EXCEPTIONS
     switch (part) {
@@ skipping 64 matching lines @@
             break;
         case InnerSpinButtonPart:
             paintStepper(states, context, zoomedRect, zoomFactor, scrollableArea);
             break;
         default:
             break;
     }
 }
 
 }