Only test optimizing compilation in helper thread compilation test.

runtime/vm/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 VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 320 matching lines @@
     return Handle(isolate->current_zone(), raw_ptr);
   }
   static Object* ReadOnlyHandle() {
     Object* obj = reinterpret_cast<Object*>(
         Dart::AllocateReadOnlyHandle());
     initializeHandle(obj, Object::null());
     return obj;
   }
 
   static Object& Handle() {
-    return Handle(Isolate::Current(), null_);
+    return Handle(Thread::Current()->zone(), null_);
   }
 
   static Object& Handle(Zone* zone) {
     return Handle(zone, null_);
   }
   // DEPRECATED: Use Zone version.
   static Object& Handle(Isolate* isolate) {
     return Handle(isolate->current_zone(), null_);
   }
 
   static Object& Handle(RawObject* raw_ptr) {
-    return Handle(Isolate::Current(), raw_ptr);
+    return Handle(Thread::Current()->zone(), raw_ptr);
   }
 
   static Object& ZoneHandle(Zone* zone, RawObject* raw_ptr) {
     Object* obj = reinterpret_cast<Object*>(
         VMHandles::AllocateZoneHandle(zone));
     initializeHandle(obj, raw_ptr);
     return *obj;
   }
 
   static Object& ZoneHandle() {
@@ skipping 7665 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_