Backed out changeset fe9dcdf48551 (bug 879374) for mochitest-3 crashes.

widget/cocoa/nsChildView.mm

@@ -4600,10 +4600,6 @@ static int32_t RoundUp(double aDouble)
     mouseEvent->buttons |= nsMouseEvent::e5thButtonFlag;
   }
 
-  if ([aMouseEvent subtype] == NSTabletPointEventSubtype) {
-    mouseEvent->pressure = [aMouseEvent pressure];
-  }
-
   NS_OBJC_END_TRY_ABORT_BLOCK;
 }