Revert of Fix slow repaint object registration

Source/core/layout/LayoutObject.cpp

Index: Source/core/layout/LayoutObject.cpp
diff --git a/Source/core/layout/LayoutObject.cpp b/Source/core/layout/LayoutObject.cpp
index c20b504fa6617132f02c64340e496033b1e0e1bb..0fe7c9728b8669ad334778f128161090e6034ca3 100644
--- a/Source/core/layout/LayoutObject.cpp
+++ b/Source/core/layout/LayoutObject.cpp
@@ -1836,6 +1836,11 @@
         setShouldDoFullPaintInvalidation();
 }
 
+static inline bool layoutObjectHasBackground(const LayoutObject* layoutObject)
+{
+    return layoutObject && layoutObject->hasBackground();
+}
+
 void LayoutObject::styleWillChange(StyleDifference diff, const ComputedStyle& newStyle)
 {
     if (m_style) {
@@ -1879,6 +1884,37 @@
         }
     } else {
         s_affectsParentBlock = false;
+    }
+
+    if (view()->frameView()) {
+        bool shouldBlitOnFixedBackgroundImage = false;
+        if (RuntimeEnabledFeatures::fastMobileScrollingEnabled()) {
+            // On low-powered/mobile devices, preventing blitting on a scroll can cause noticeable delays
+            // when scrolling a page with a fixed background image. As an optimization, assuming there are
+            // no fixed positoned elements on the page, we can acclerate scrolling (via blitting) if we
+            // ignore the CSS property "background-attachment: fixed".
+            shouldBlitOnFixedBackgroundImage = true;
+        }
+        bool newStyleSlowScroll = !shouldBlitOnFixedBackgroundImage && newStyle.hasFixedBackgroundImage();
+        bool oldStyleSlowScroll = m_style && !shouldBlitOnFixedBackgroundImage && m_style->hasFixedBackgroundImage();
+
+        bool drawsRootBackground = isDocumentElement() || (isBody() && !layoutObjectHasBackground(document().documentElement()->layoutObject()));
+        if (drawsRootBackground && !shouldBlitOnFixedBackgroundImage) {
+            if (view()->compositor()->supportsFixedRootBackgroundCompositing()) {
+                if (newStyleSlowScroll && newStyle.hasEntirelyFixedBackground())
+                    newStyleSlowScroll = false;
+
+                if (oldStyleSlowScroll && m_style->hasEntirelyFixedBackground())
+                    oldStyleSlowScroll = false;
+            }
+        }
+
+        if (oldStyleSlowScroll != newStyleSlowScroll) {
+            if (oldStyleSlowScroll)
+                view()->frameView()->removeSlowRepaintObject();
+            if (newStyleSlowScroll)
+                view()->frameView()->addSlowRepaintObject();
+        }
     }
 
     // Elements with non-auto touch-action will send a SetTouchAction message
@@ -2437,9 +2473,6 @@
         removeShapeImageClient(m_style->shapeOutside());
     }
     ResourceLoadPriorityOptimizer::resourceLoadPriorityOptimizer()->removeLayoutObject(this);
-
-    if (frameView())
-        setIsSlowRepaintObject(false);
 }
 
 void LayoutObject::insertedIntoTree()
@@ -3237,18 +3270,6 @@
     setShouldDoFullPaintInvalidationIncludingNonCompositingDescendantsInternal(this);
 }
 
-void LayoutObject::setIsSlowRepaintObject(bool isSlowRepaintObject)
-{
-    ASSERT(frameView());
-    if (m_bitfields.isSlowRepaintObject() == isSlowRepaintObject)
-        return;
-    m_bitfields.setIsSlowRepaintObject(isSlowRepaintObject);
-    if (isSlowRepaintObject)
-        frameView()->addSlowRepaintObject();
-    else
-        frameView()->removeSlowRepaintObject();
-}
-
 } // namespace blink
 
 #ifndef NDEBUG