Remove the dependency of Zone on Isolate

test/unittests/test-utils.h

 // Copyright 2014 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_UNITTESTS_TEST_UTILS_H_
 #define V8_UNITTESTS_TEST_UTILS_H_
 
 #include "include/v8.h"
 #include "src/base/macros.h"
 #include "src/base/utils/random-number-generator.h"
@@ skipping 74 matching lines @@
   }
   base::RandomNumberGenerator* random_number_generator() const;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TestWithIsolate);
 };
 
 
 class TestWithZone : public TestWithIsolate {
  public:
-  TestWithZone() : zone_(isolate()) {}
+  TestWithZone() {}
   virtual ~TestWithZone();
 
   Zone* zone() { return &zone_; }
 
  private:
   Zone zone_;
 
   DISALLOW_COPY_AND_ASSIGN(TestWithZone);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_UNITTESTS_TEST_UTILS_H_