Add infrastructure for partial layouts

Source/core/rendering/RenderObject.cpp

Index: Source/core/rendering/RenderObject.cpp
diff --git a/Source/core/rendering/RenderObject.cpp b/Source/core/rendering/RenderObject.cpp
index 2369edf2f2c846c3a23a46fed041ecbf15e6c747..9b081370286c97828de5ec280e5b5d26c4806b9a 100644
--- a/Source/core/rendering/RenderObject.cpp
+++ b/Source/core/rendering/RenderObject.cpp
@@ -733,6 +733,12 @@ void RenderObject::checkBlockPositionedObjectsNeedLayout()
     if (isRenderBlock())
         toRenderBlock(this)->checkPositionedObjectsNeedLayout();
 }
+
+void RenderObject::checkNotInPartialLayout()
+{
+    // During partial layout, setNeedsLayout(true or false) should not be called.
+    ASSERT(!frameView()->partialLayout().isStopping());
+}
 #endif
 
 void RenderObject::setPreferredLogicalWidthsDirty(MarkingBehavior markParents)