Fix int overflow in window.moveBy

third_party/WebKit/Source/platform/geometry/IntPoint.h

 /*
  * Copyright (C) 2004, 2005, 2006 Apple Computer, Inc.  All rights reserved.
  * Copyright (C) 2013 Google 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
@@ skipping 13 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef IntPoint_h
 #define IntPoint_h
 
 #include "platform/geometry/IntSize.h"
 #include "wtf/Allocator.h"
 #include "wtf/Forward.h"
 #include "wtf/MathExtras.h"
+#include "wtf/SaturatedArithmetic.h"
 #include "wtf/VectorTraits.h"
 
 #if OS(MACOSX)
 typedef struct CGPoint CGPoint;
 
 #ifdef __OBJC__
 #import <Foundation/Foundation.h>
 #endif
 #endif
 
@@ skipping 10 matching lines @@
 
     int x() const { return m_x; }
     int y() const { return m_y; }
 
     void setX(int x) { m_x = x; }
     void setY(int y) { m_y = y; }
 
     void move(const IntSize& s) { move(s.width(), s.height()); }
     void moveBy(const IntPoint& offset) { move(offset.x(), offset.y()); }
     void move(int dx, int dy) { m_x += dx; m_y += dy; }
+    void saturatedMove(int dx, int dy)
+    {
+        m_x = saturatedAddition(m_x, dx);
+        m_y = saturatedAddition(m_y, dy);
+    }
+
     void scale(float sx, float sy)
     {
         m_x = lroundf(static_cast<float>(m_x * sx));
         m_y = lroundf(static_cast<float>(m_y * sy));
     }
 
     IntPoint expandedTo(const IntPoint& other) const
     {
         return IntPoint(m_x > other.m_x ? m_x : other.m_x,
             m_y > other.m_y ? m_y : other.m_y);
@@ skipping 90 matching lines @@
 inline int IntPoint::distanceSquaredToPoint(const IntPoint& point) const
 {
     return ((*this) - point).diagonalLengthSquared();
 }
 
 } // namespace blink
 
 WTF_ALLOW_MOVE_INIT_AND_COMPARE_WITH_MEM_FUNCTIONS(blink::IntPoint);
 
 #endif // IntPoint_h