Force compositing inputs to be clean for getBoundingClientRect

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc.
  * All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
@@ skipping 1103 matching lines @@
   // We don't use absoluteBoundingBoxRect() because it can return an IntRect
   // larger the actual size by 1px. crbug.com/470503
   rect.intersect(document().view()->contentsToViewport(
       roundedIntRect(layoutObject()->absoluteBoundingBoxFloatRect())));
   return rect;
 }
 
 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;
 
   if (isSVGElement() && !elementLayoutObject->isSVGRoot()) {
     // Get the bounding rectangle from the SVG model.
     if (toSVGElement(this)->isSVGGraphicsElement())
       quads.push_back(elementLayoutObject->localToAbsoluteQuad(
           elementLayoutObject->objectBoundingBox()));
     return;
@@ skipping 2996 matching lines @@
 }
 
 DEFINE_TRACE_WRAPPERS(Element) {
   if (hasRareData()) {
     visitor->traceWrappers(elementRareData());
   }
   ContainerNode::traceWrappers(visitor);
 }
 
 }  // namespace blink