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

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 7a778aa8dfc8f2c070747c7e2903ea11cfa59b25..caf5c7ed77ddb838af6063eb06c90b85c048f2b5 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -774,9 +774,12 @@ int Element::clientHeight() {
 }
 
 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;
@@ -789,9 +792,12 @@ double Element::scrollLeft() {
 }
 
 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;
@@ -804,11 +810,14 @@ double Element::scrollTop() {
 }
 
 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 {
@@ -820,11 +829,14 @@ void Element::setScrollLeft(double newLeft) {
 }
 
 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 {
@@ -836,9 +848,12 @@ void Element::setScrollTop(double newTop) {
 }
 
 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());
@@ -851,9 +866,12 @@ int Element::scrollWidth() {
 }
 
 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());
@@ -873,11 +891,14 @@ void Element::scrollBy(double x, double y) {
 }
 
 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);
@@ -892,11 +913,14 @@ void Element::scrollTo(double x, double y) {
 }
 
 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);