Rename Closure instance field type_arguments_ to instantiator_.

runtime/vm/raw_object.h

 // Copyright (c) 2012, 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 RUNTIME_VM_RAW_OBJECT_H_
 #define RUNTIME_VM_RAW_OBJECT_H_
 
 #include "platform/assert.h"
 #include "vm/atomic.h"
 #include "vm/globals.h"
@@ skipping 1764 matching lines @@
     return reinterpret_cast<RawObject**>(&ptr()->mixin_types_);
   }
 };
 
 
 class RawClosure : public RawInstance {
  private:
   RAW_HEAP_OBJECT_IMPLEMENTATION(Closure);
 
   RawObject** from() {
-    return reinterpret_cast<RawObject**>(&ptr()->type_arguments_);
+    return reinterpret_cast<RawObject**>(&ptr()->instantiator_);
   }
 
-  RawTypeArguments* type_arguments_;
+  // No instance fields should be declared before the following 3 fields whose
+  // offsets must be identical in Dart and C++.
+
+  // These 3 fields are also declared in the Dart source of class _Closure.
+  RawTypeArguments* instantiator_;
   RawFunction* function_;
   RawContext* context_;
 
   RawObject** to() { return reinterpret_cast<RawObject**>(&ptr()->context_); }
 };
 
 
 class RawNumber : public RawInstance {
   RAW_OBJECT_IMPLEMENTATION(Number);
 };
@@ skipping 634 matching lines @@
   COMPILE_ASSERT(kExternalTypedDataInt8ArrayCid ==
                  kTypedDataInt8ArrayViewCid + 15);
   COMPILE_ASSERT(kByteBufferCid == kExternalTypedDataInt8ArrayCid + 14);
   COMPILE_ASSERT(kNullCid == kByteBufferCid + 1);
   return (kNullCid - kTypedDataInt8ArrayCid);
 }
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_RAW_OBJECT_H_