Remove the dependency of Zone on Isolate

src/zone.cc

 // 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.
 
 #include <string.h>
 
 #include "src/v8.h"
 #include "src/zone-inl.h"
 
 namespace v8 {
@@ skipping 26 matching lines @@
   // Computes the address of the nth byte in this segment.
   Address address(int n) const {
     return Address(this) + n;
   }
 
   Segment* next_;
   int size_;
 };
 
 
-Zone::Zone(Isolate* isolate)
+Zone::Zone()
     : allocation_size_(0),
       segment_bytes_allocated_(0),
       position_(0),
       limit_(0),
-      segment_head_(NULL),
-      isolate_(isolate) {
-}
+      segment_head_(NULL) {}
 
 
 Zone::~Zone() {
   DeleteAll();
   DeleteKeptSegment();
 
   DCHECK(segment_bytes_allocated_ == 0);
 }
 
 
@@ skipping 186 matching lines @@
     V8::FatalProcessOutOfMemory("Zone");
     return NULL;
   }
   limit_ = segment->end();
   DCHECK(position_ <= limit_);
   return result;
 }
 
 
 } }  // namespace v8::internal