Take ast node id counting away from Isolate.

src/zone.h

 // Copyright 2012 the V8 project 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 V8_ZONE_H_
 #define V8_ZONE_H_
 
 #include <limits>
 
 #include "src/allocation.h"
@@ skipping 45 matching lines @@
   // Deletes the last small segment kept around by DeleteAll(). You
   // may no longer allocate in the Zone after a call to this method.
   void DeleteKeptSegment();
 
   // Returns true if more memory has been allocated in zones than
   // the limit allows.
   inline bool excess_allocation();
 
   inline void adjust_segment_bytes_allocated(int delta);
 
-  inline unsigned allocation_size() { return allocation_size_; }
+  inline unsigned allocation_size() const { return allocation_size_; }
 
-  inline Isolate* isolate() { return isolate_; }
+  inline Isolate* isolate() const { return isolate_; }
 
  private:
   friend class Isolate;
 
   // All pointers returned from New() have this alignment.  In addition, if the
   // object being allocated has a size that is divisible by 8 then its alignment
   // will be 8. ASan requires 8-byte alignment.
 #ifdef V8_USE_ADDRESS_SANITIZER
   static const int kAlignment = 8;
   STATIC_ASSERT(kPointerSize <= 8);
@@ skipping 161 matching lines @@
   void operator delete(void* pointer) { UNREACHABLE(); }
   void operator delete(void* pointer, Zone* zone) { UNREACHABLE(); }
 };
 
 
 typedef TemplateHashMapImpl<ZoneAllocationPolicy> ZoneHashMap;
 
 } }  // namespace v8::internal
 
 #endif  // V8_ZONE_H_