[PE] Don't call CompositedScrollsWithRespectTo during raster invalidation

It is redundant with the call to UsesCompositedScrolling just below, and
is equivalent to UsesCompositedScrolling + object != paint_invalidation_container.
UsesCompositedScrolling calls two methods plus a virtual, so may be slow.

Bug: 818709

Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: Iab617e3941563ac1994e5732359cf691442a2b7e
Reviewed-on: https://chromium-review.googlesource.com/959444
Commit-Queue: vmpstr <vmpstr@chromium.org>
Reviewed-by: vmpstr <vmpstr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542667}

third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp

@@ -308,13 +308,10 @@ void ObjectPaintInvalidator::SetBackingNeedsPaintInvalidationInRect(
       squashing_layer->SetNeedsDisplayInRect(EnclosingIntRect(rect), reason,
                                              object_);
     }
-  } else if (object_.CompositedScrollsWithRespectTo(
-                 paint_invalidation_container)) {
-    layer.GetCompositedLayerMapping()->SetScrollingContentsNeedDisplayInRect(
-        rect, reason, object_);
   } else if (paint_invalidation_container.UsesCompositedScrolling()) {
-    DCHECK(object_ == paint_invalidation_container);
-    if (reason ==
+    // If object_ is not paint_invalidation_container, then it scrolls.
+    if (&object_ != paint_invalidation_container ||
+        reason ==
             PaintInvalidationReason::kBackgroundOnScrollingContentsLayer ||
         reason == PaintInvalidationReason::kCaret) {
       layer.GetCompositedLayerMapping()->SetScrollingContentsNeedDisplayInRect(