Bug 943846 - Don't constrain generated display-ports to composition bounds. r=kats

gfx/layers/ipc/AsyncPanZoomController.cpp

@@ -1213,21 +1213,6 @@ const CSSRect AsyncPanZoomController::CalculatePendingDisplayPort(
     scrollOffset.y = scrollableRect.y;
   }
 
-  // FIXME/bug 936500: Make sure the displayport contains the composition
-  // bounds. This is to work around a layout bug that means if a display item's
-  // corresponding displayport doesn't contain its frame's bounds, it may get
-  // optimised out and the layer won't get created.
-  if (displayPort.x + displayPort.width < compositionBounds.width) {
-    displayPort.x = -(displayPort.width - compositionBounds.width);
-  } else if (displayPort.x > 0) {
-    displayPort.x = 0;
-  }
-  if (displayPort.y + displayPort.height < compositionBounds.height) {
-    displayPort.y = -(displayPort.height - compositionBounds.height);
-  } else if (displayPort.y > 0) {
-    displayPort.y = 0;
-  }
-
   CSSRect shiftedDisplayPort = displayPort + scrollOffset;
   return scrollableRect.ClampRect(shiftedDisplayPort) - scrollOffset;
 }