Remove the dependency of Zone on 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 18 matching lines @@
 
 // Note: There is no need to initialize the Zone; the first time an
 // allocation is attempted, a segment of memory will be requested
 // through a call to malloc().
 
 // Note: The implementation is inherently not thread safe. Do not use
 // from multi-threaded code.
 
 class Zone {
  public:
-  explicit Zone(Isolate* isolate);
+  Zone();
   ~Zone();
   // Allocate 'size' bytes of memory in the Zone; expands the Zone by
   // allocating new segments of memory on demand using malloc().
   void* New(int size);
 
   template <typename T>
   T* NewArray(int length) {
     CHECK(std::numeric_limits<int>::max() / static_cast<int>(sizeof(T)) >
           length);
     return static_cast<T*>(New(length * sizeof(T)));
   }
 
   // Deletes all objects and free all memory allocated in the Zone. Keeps one
   // small (size <= kMaximumKeptSegmentSize) segment around if it finds one.
   void DeleteAll();
 
   // 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() const { return allocation_size_; }
 
-  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);
 #else
@@ skipping 33 matching lines @@
   // Deletes the given segment. Does not touch the segment chain.
   INLINE(void DeleteSegment(Segment* segment, int size));
 
   // The free region in the current (front) segment is represented as
   // the half-open interval [position, limit). The 'position' variable
   // is guaranteed to be aligned as dictated by kAlignment.
   Address position_;
   Address limit_;
 
   Segment* segment_head_;
-  Isolate* isolate_;
 };
 
 
 // ZoneObject is an abstraction that helps define classes of objects
 // allocated in the Zone. Use it as a base class; see ast.h.
 class ZoneObject {
  public:
   // Allocate a new ZoneObject of 'size' bytes in the Zone.
   INLINE(void* operator new(size_t size, Zone* zone));
 
@@ skipping 106 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_