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..aa85a2e8765fb6eb4441ab8c774996766f16ae77 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)
@@ -2761,6 +2767,11 @@ bool RenderObject::nodeAtPoint(const HitTestRequest&, HitTestResult&, const HitT
     return false;
 }
 
+FrameView* RenderObject::frameView() const
+{
+    return document().view();
+}
+
 void RenderObject::scheduleRelayout()
 {
     if (isRenderView()) {