Add workaround to avoid crashing when calling LocalBorderBoxProperties

In the presence of rare bugs, it is apparently possible to have a
graphics layer but no LocalBorderBoxProperties.

Bug: 1137883

Change-Id: I17d65c6ca04d15254efe9b2d13e3de905b59567e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2474918
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#817565}

third_party/blink/renderer/core/paint/compositing/compositing_layer_property_updater.cc

@@ -44,12 +44,6 @@ void CompositingLayerPropertyUpdater::Update(const LayoutObject& object) {
          object.GetDocument().Printing() ||
          !object.CanBeCompositedForDirectReasons());
 
-  // TODO(chrishtr): this should never happen, but does in practice and
-  // we haven't been able to find all of the cases where it happens yet.
-  // Once we find more of them, try to remove this.
-  if (!fragment_data.HasLocalBorderBoxProperties())
-    return;
-
   PhysicalOffset layout_snapped_paint_offset =
       fragment_data.PaintOffset() - paint_layer->SubpixelAccumulation();
   IntPoint snapped_paint_offset = RoundedIntPoint(layout_snapped_paint_offset);

third_party/blink/renderer/core/paint/fragment_data.h

@@ -150,6 +150,12 @@ class CORE_EXPORT FragmentData {
   //   ancestor transform space.
   PropertyTreeStateOrAlias LocalBorderBoxProperties() const {
     DCHECK(HasLocalBorderBoxProperties());
+
+    // TODO(chrishtr): this should never happen, but does in practice and
+    // we haven't been able to find all of the cases where it happens yet.
+    // See crbug.com/1137883. Once we find more of them, remove this.
+    if (!rare_data_ || !rare_data_->local_border_box_properties)
+      return PropertyTreeState::Root();
     return rare_data_->local_border_box_properties->GetPropertyTreeState();
   }
   bool HasLocalBorderBoxProperties() const {