Force compositing inputs to be clean for getBoundingClientRect

third_party/WebKit/Source/core/dom/Element.cpp

Index: third_party/WebKit/Source/core/dom/Element.cpp
diff --git a/third_party/WebKit/Source/core/dom/Element.cpp b/third_party/WebKit/Source/core/dom/Element.cpp
index d5ea539ee3527b4a3f90bb8e3b32abb76b499bdf..35b5897441f5ac726b50add9068003417590a9f4 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -1121,6 +1121,14 @@ IntRect Element::visibleBoundsInVisualViewport() const {
 void Element::clientQuads(Vector<FloatQuad>& quads) {
   document().updateStyleAndLayoutIgnorePendingStylesheetsForNode(this);
 
+  // To ensure that the quads are correct for position:sticky elements or
+  // descendants, compositing inputs must be clean. In most cases this should
+  // already be true but not always e.g. if javascript has dirtied layout/style
+  // and then requested bounds on an element without yielding.
+  FrameView* view = document().view();
+  if (inActiveDocument() && view)
+    view->updateLifecycleToCompositingCleanPlusScrolling();

[flackr, 2017/01/20 02:47:02]

I suspect we'll need to do this for a lot of other methods, maybe we should add
a private helper that ensures clean compositing inputs. With this here we don't
need to updateStyleAndLayout above do we?

[smcgruer, 2017/01/20 16:07:09]

Done. I think it could also be just an anon function if that is preferential.
I'm unsure. It appears to work, but I don't know the full impact of doing this.
Chris?

+
   LayoutObject* elementLayoutObject = layoutObject();
   if (!elementLayoutObject)
     return;