Only create sticky position constraints for constrained sticky position.

third_party/WebKit/Source/core/frame/FrameView.cpp

Index: third_party/WebKit/Source/core/frame/FrameView.cpp
diff --git a/third_party/WebKit/Source/core/frame/FrameView.cpp b/third_party/WebKit/Source/core/frame/FrameView.cpp
index a7254f82cf1954e4841113cd7d203798305245b5..92ba0eb06d50e6d7570f58d6bee9367c7354881e 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.cpp
+++ b/third_party/WebKit/Source/core/frame/FrameView.cpp
@@ -1767,8 +1767,9 @@ bool FrameView::InvalidateViewportConstrainedObjects() {
        *viewport_constrained_objects_) {
     LayoutObject* layout_object = viewport_constrained_object;
     LayoutItem layout_item = LayoutItem(layout_object);
-    ASSERT(layout_item.Style()->HasViewportConstrainedPosition());
-    ASSERT(layout_item.HasLayer());
+    DCHECK(layout_item.Style()->HasViewportConstrainedPosition() ||
+           layout_item.Style()->HasStickyConstrainedPosition());
+    DCHECK(layout_item.HasLayer());
     PaintLayer* layer = LayoutBoxModel(layout_item).Layer();
 
     if (layer->IsPaintInvalidationContainer())