Put LayoutAnalyzer back behind disabled-by-default-blink.debug.layout.

Source/core/layout/LayoutAnalyzer.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef LayoutAnalyzer_h
 #define LayoutAnalyzer_h
 
 #include "wtf/PassRefPtr.h"
 
 namespace blink {
@@ skipping 29 matching lines @@
     };
     static const size_t NumCounters = 19;
 
     class Scope {
     public:
         explicit Scope(const LayoutObject&);
         ~Scope();
 
     private:
         const LayoutObject& m_layoutObject;
-        LayoutAnalyzer& m_analyzer;
+        LayoutAnalyzer* m_analyzer;
     };
 
     LayoutAnalyzer() { }
 
     void reset();
     void push(const LayoutObject&);
     void pop(const LayoutObject&);
 
     void increment(Counter counter, unsigned delta = 1)
     {
         m_counters[counter] += delta;
     }
 
     void recordCounters();
 
     PassRefPtr<TracedValue> toTracedValue();
 
 private:
     const char* nameForCounter(Counter) const;
 
     double m_startMs;
     unsigned m_depth;
     unsigned m_counters[NumCounters];
 };
 
 } // namespace blink
 
 #endif // LayoutAnalyzer_h