Merges two WK fixes for RenderLayer::backgroundIsKnownToBeOpaque.

Source/core/rendering/RenderLayer.cpp

Index: Source/core/rendering/RenderLayer.cpp
diff --git a/Source/core/rendering/RenderLayer.cpp b/Source/core/rendering/RenderLayer.cpp
index 26f38033c20aa1af9f8a188b5dedb715329b760e..d4d3da94198f071f5a35bf11468ccd3ff291b60f 100644
--- a/Source/core/rendering/RenderLayer.cpp
+++ b/Source/core/rendering/RenderLayer.cpp
@@ -5550,6 +5550,11 @@ bool RenderLayer::backgroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect)
     if (paintsWithTransparency(PaintBehaviorNormal))
         return false;
 
+    // We can't use hasVisibleContent(), because that will be true if our renderer is hidden, but some child
+    // is visible and that child doesn't cover the entire rect.
+    if (renderer()->style()->visibility() != VISIBLE)
+        return false;
+
     if (paintsWithFilters() && renderer()->style()->filter().hasFilterThatAffectsOpacity())
         return false;
 
@@ -5565,8 +5570,15 @@ bool RenderLayer::backgroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect)
 
     // FIXME: We currently only check the immediate renderer,
     // which will miss many cases.
-    return renderer()->backgroundIsKnownToBeOpaqueInRect(localRect)
-        || listBackgroundIsKnownToBeOpaqueInRect(posZOrderList(), localRect)
+    if (renderer()->backgroundIsKnownToBeOpaqueInRect(localRect))
+        return true;
+
+    // We can't consult child layers if we clip, since they might cover
+    // parts of the rect that are clipped out.
+    if (renderer()->hasOverflowClip())
+        return false;
+
+    return listBackgroundIsKnownToBeOpaqueInRect(posZOrderList(), localRect)
         || listBackgroundIsKnownToBeOpaqueInRect(negZOrderList(), localRect)
         || listBackgroundIsKnownToBeOpaqueInRect(normalFlowList(), localRect);
 }