Make it possibe to lock the fixedLayoutSize

Source/core/platform/ScrollView.h

Index: Source/core/platform/ScrollView.h
diff --git a/Source/core/platform/ScrollView.h b/Source/core/platform/ScrollView.h
index 4b2de996058ee35619067f279087e04c7f27e75a..49712095e5a687a3b092b73a717d4217f74884bb 100644
--- a/Source/core/platform/ScrollView.h
+++ b/Source/core/platform/ScrollView.h
@@ -138,6 +138,8 @@ public:
     void setFixedLayoutSize(const IntSize&);
     bool useFixedLayout() const;
     void setUseFixedLayout(bool enable);
+    void setFixedLayoutSizeLock(bool);
+    bool fixedLayoutSizeLock() const;
 
     // Functions for getting/setting the size of the document contained inside the ScrollView (as an IntSize or as individual width and height
     // values).
@@ -325,6 +327,7 @@ private:
     IntPoint m_panScrollIconPoint;
     bool m_drawPanScrollIcon;
     bool m_useFixedLayout;
+    bool m_fixedLayoutSizeLock;
 
     bool m_paintsEntireContents;
     bool m_clipsRepaints;