Fixed Inconsistent behaviour of custom-scrollbar

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index 0aead4777869975461aa32155082b51948005ade..adea646094ec033c0a3364a70632fcfb0ebb7e8e 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -920,6 +920,9 @@ void FrameView::layout(bool allowSubtree)
     if (!inSubtreeLayout && !toRenderView(rootForThisLayout)->document().printing())
         adjustViewSize();
 
+    if (rootForThisLayout->needsLayout())
+        performLayout(rootForThisLayout, inSubtreeLayout);

[esprehn, 2014/09/19 05:06:52]

Other places call adjustViewSize without a second layout, are you sure this is
right? Should adjustViewSize do this?

[MuVen, 2014/09/19 16:19:30]

During adjustViewSize call, in the API FrameView::setContentsSize, after calling
ScrollView::setContentsSize(size); sets the rootObject needsLayout.

+
     layer->updateLayerPositionsAfterLayout();
 
     if (m_doFullPaintInvalidation)