Don't force-update style and layout in Document::scrollingElement

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 756 matching lines @@
 
   if (LayoutBox* layoutObject = layoutBox())
     return adjustLayoutUnitForAbsoluteZoom(
                LayoutUnit(layoutObject->pixelSnappedClientHeight()),
                layoutObject->styleRef())
         .round();
   return 0;
 }
 
 double Element::scrollLeft() {
+  if (!inActiveDocument())

[chrishtr, 2017/01/11 21:43:19]

These were needed because updateStyleAndLayoutIgnorePendingStylesheetsForNode
early-outs if the element is not in the document, and hence the document's
lifecycle remains dirty, triggering the assert. However, if the element is 
not in the document, the only possible return value is 0 anyway.

+    return 0;
+
   document().updateStyleAndLayoutIgnorePendingStylesheetsForNode(this);
 
-  if (document().scrollingElement() == this) {
+  if (document().scrollingElementNoLayout() == this) {
     if (document().domWindow())
       return document().domWindow()->scrollX();
     return 0;
   }
 
   if (LayoutBox* box = layoutBox())
     return adjustScrollForAbsoluteZoom(box->scrollLeft(), *box);
 
   return 0;
 }
 
 double Element::scrollTop() {
+  if (!inActiveDocument())
+    return 0;
+
   document().updateStyleAndLayoutIgnorePendingStylesheetsForNode(this);
 
-  if (document().scrollingElement() == this) {
+  if (document().scrollingElementNoLayout() == this) {
     if (document().domWindow())
       return document().domWindow()->scrollY();
     return 0;
   }
 
   if (LayoutBox* box = layoutBox())
     return adjustScrollForAbsoluteZoom(box->scrollTop(), *box);
 
   return 0;
 }
 
 void Element::setScrollLeft(double newLeft) {
+  if (!inActiveDocument())
+    return;
+
   document().updateStyleAndLayoutIgnorePendingStylesheetsForNode(this);
 
   newLeft = ScrollableArea::normalizeNonFiniteScroll(newLeft);
 
-  if (document().scrollingElement() == this) {
+  if (document().scrollingElementNoLayout() == this) {
     if (LocalDOMWindow* window = document().domWindow())
       window->scrollTo(newLeft, window->scrollY());
   } else {
     LayoutBox* box = layoutBox();
     if (box)
       box->setScrollLeft(
           LayoutUnit::fromFloatRound(newLeft * box->style()->effectiveZoom()));
   }
 }
 
 void Element::setScrollTop(double newTop) {
+  if (!inActiveDocument())
+    return;
+
   document().updateStyleAndLayoutIgnorePendingStylesheetsForNode(this);
 
   newTop = ScrollableArea::normalizeNonFiniteScroll(newTop);
 
-  if (document().scrollingElement() == this) {
+  if (document().scrollingElementNoLayout() == this) {
     if (LocalDOMWindow* window = document().domWindow())
       window->scrollTo(window->scrollX(), newTop);
   } else {
     LayoutBox* box = layoutBox();
     if (box)
       box->setScrollTop(
           LayoutUnit::fromFloatRound(newTop * box->style()->effectiveZoom()));
   }
 }
 
 int Element::scrollWidth() {
+  if (!inActiveDocument())
+    return 0;
+
   document().updateStyleAndLayoutIgnorePendingStylesheetsForNode(this);
 
-  if (document().scrollingElement() == this) {
+  if (document().scrollingElementNoLayout() == this) {
     if (document().view())
       return adjustForAbsoluteZoom(document().view()->contentsWidth(),
                                    document().frame()->pageZoomFactor());
     return 0;
   }
 
   if (LayoutBox* box = layoutBox())
     return adjustForAbsoluteZoom(box->pixelSnappedScrollWidth(), box);
   return 0;
 }
 
 int Element::scrollHeight() {
+  if (!inActiveDocument())
+    return 0;
+
   document().updateStyleAndLayoutIgnorePendingStylesheetsForNode(this);
 
-  if (document().scrollingElement() == this) {
+  if (document().scrollingElementNoLayout() == this) {
     if (document().view())
       return adjustForAbsoluteZoom(document().view()->contentsHeight(),
                                    document().frame()->pageZoomFactor());
     return 0;
   }
 
   if (LayoutBox* box = layoutBox())
     return adjustForAbsoluteZoom(box->pixelSnappedScrollHeight(), box);
   return 0;
 }
 
 void Element::scrollBy(double x, double y) {
   ScrollToOptions scrollToOptions;
   scrollToOptions.setLeft(x);
   scrollToOptions.setTop(y);
   scrollBy(scrollToOptions);
 }
 
 void Element::scrollBy(const ScrollToOptions& scrollToOptions) {
+  if (!inActiveDocument())
+    return;
+
   // FIXME: This should be removed once scroll updates are processed only after
   // the compositing update. See http://crbug.com/420741.
   document().updateStyleAndLayoutIgnorePendingStylesheetsForNode(this);
 
-  if (document().scrollingElement() == this) {
+  if (document().scrollingElementNoLayout() == this) {
     scrollFrameBy(scrollToOptions);
   } else {
     scrollLayoutBoxBy(scrollToOptions);
   }
 }
 
 void Element::scrollTo(double x, double y) {
   ScrollToOptions scrollToOptions;
   scrollToOptions.setLeft(x);
   scrollToOptions.setTop(y);
   scrollTo(scrollToOptions);
 }
 
 void Element::scrollTo(const ScrollToOptions& scrollToOptions) {
+  if (!inActiveDocument())
+    return;
+
   // FIXME: This should be removed once scroll updates are processed only after
   // the compositing update. See http://crbug.com/420741.
   document().updateStyleAndLayoutIgnorePendingStylesheetsForNode(this);
 
-  if (document().scrollingElement() == this) {
+  if (document().scrollingElementNoLayout() == this) {
     scrollFrameTo(scrollToOptions);
   } else {
     scrollLayoutBoxTo(scrollToOptions);
   }
 }
 
 void Element::scrollLayoutBoxBy(const ScrollToOptions& scrollToOptions) {
   double left =
       scrollToOptions.hasLeft()
           ? ScrollableArea::normalizeNonFiniteScroll(scrollToOptions.left())
@@ skipping 3200 matching lines @@
 }
 
 DEFINE_TRACE_WRAPPERS(Element) {
   if (hasRareData()) {
     visitor->traceWrappers(elementRareData());
   }
   ContainerNode::traceWrappers(visitor);
 }
 
 }  // namespace blink