Migrate most uses of StackZone(Isolate*) to Thread*.

runtime/vm/unit_test.h

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_UNIT_TEST_H_
 #define VM_UNIT_TEST_H_
 
 #include "include/dart_native_api.h"
 
 #include "platform/globals.h"
@@ skipping 16 matching lines @@
   static const dart::TestCase kRegister##name(Dart_Test##name, #name);         \
   void Dart_Test##name()
 
 // The TEST_CASE macro is used for tests that need an isolate and zone
 // in order to test its functionality.
 #define TEST_CASE(name)                                                        \
   static void Dart_TestHelper##name();                                         \
   UNIT_TEST_CASE(name)                                                         \
   {                                                                            \
     TestIsolateScope __test_isolate__;                                         \
-    StackZone __zone__(__test_isolate__.isolate());                            \
-    HandleScope __hs__(__test_isolate__.isolate());                            \
+    Thread* __thread__ = Thread::Current();                                    \
+    ASSERT(__thread__->isolate() == __test_isolate__.isolate());               \
+    StackZone __zone__(__thread__);                                            \
+    HandleScope __hs__(__thread__);                                            \
     Dart_TestHelper##name();                                                   \
   }                                                                            \
   static void Dart_TestHelper##name()
 
 // The ASSEMBLER_TEST_GENERATE macro is used to generate a unit test
 // for the assembler.
 #define ASSEMBLER_TEST_GENERATE(name, assembler)                               \
   void AssemblerTestGenerate##name(Assembler* assembler)
 
 // The ASSEMBLER_TEST_EXTERN macro is used to declare a unit test
@@ skipping 375 matching lines @@
       }                                                                        \
     } else {                                                                   \
       dart::Expect(__FILE__, __LINE__).Fail("expected True, but was '%s'\n",   \
           #handle);                                                            \
     }                                                                          \
   } while (0)
 
 }  // namespace dart
 
 #endif  // VM_UNIT_TEST_H_