Fixed pos objects are offset from the top of the page in paged media

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

 /*
  * Copyright (c) 2012, 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 92 matching lines @@
 ALWAYS_INLINE LayoutPoint& operator+=(LayoutPoint& a, const LayoutPoint& b) {
   a.move(b.x(), b.y());
   return a;
 }
 
 inline LayoutPoint& operator+=(LayoutPoint& a, const IntSize& b) {
   a.move(b.width(), b.height());
   return a;
 }
 
+ALWAYS_INLINE LayoutPoint& operator-=(LayoutPoint& a, const LayoutPoint& b) {
+  a.move(-b.x(), -b.y());
+  return a;
+}
+
 ALWAYS_INLINE LayoutPoint& operator-=(LayoutPoint& a, const LayoutSize& b) {
   a.move(-b.width(), -b.height());
   return a;
 }
 
 inline LayoutPoint& operator-=(LayoutPoint& a, const IntSize& b) {
   a.move(-b.width(), -b.height());
   return a;
 }
 
@@ skipping 93 matching lines @@
   return flooredLayoutPoint(FloatPoint(s));
 }
 
 // Redeclared here to avoid ODR issues.
 // See platform/testing/GeometryPrinters.h.
 void PrintTo(const LayoutPoint&, std::ostream*);
 
 }  // namespace blink
 
 #endif  // LayoutPoint_h