Null-check LayoutObject in InvalidateFilterData

In some Destroy() code-paths (in this specific case
LayoutObjectChildList::DestroyLeftoverChildren) the LayoutObject pointer
in Element (Node) will have been cleared before Destroy() is called, so
since we access the LayoutObject via the Element in this function we
need to make sure it's still present (even though we have the
LayoutObject a bit further up the callstack).

Bug: 1191089
Change-Id: I7ba46e8b06205fc09d975c4aa8a73cb448379039
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2780670
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#866040}

third_party/blink/renderer/core/layout/svg/svg_resources.cc

@@ -350,9 +350,10 @@ void SVGElementResourceClient::InvalidateFilterData() {
     return;
   if (FilterData* filter_data = filter_data_.Release())
     filter_data->Dispose();
-  LayoutObject* layout_object = element_->GetLayoutObject();
-  layout_object->SetNeedsPaintPropertyUpdate();
-  MarkFilterDataDirty();
+  if (LayoutObject* layout_object = element_->GetLayoutObject()) {
+    layout_object->SetNeedsPaintPropertyUpdate();
+    MarkFilterDataDirty();
+  }
 }
 
 void SVGElementResourceClient::MarkFilterDataDirty() {