Bug 1265513 - Do a fuzzy match when checking to see if a scroll will result in overscroll. r=botond

MozReview-Commit-ID: 3fFZHXWMnWv

gfx/layers/apz/src/Axis.cpp

@@ -459,7 +459,7 @@ bool Axis::CanScroll(ParentLayerCoord aDelta) const
     return false;
   }
 
-  return DisplacementWillOverscrollAmount(aDelta) != aDelta;
+  return fabs(DisplacementWillOverscrollAmount(aDelta) - aDelta) > COORDINATE_EPSILON;
 }
 
 CSSCoord Axis::ClampOriginToScrollableRect(CSSCoord aOrigin) const