Move no_callback_scope_depth_ and cha_ from isolate -> thread

runtime/vm/isolate.cc

 // Copyright (c) 2013, 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.
 
 #include "vm/isolate.h"
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 #include "platform/assert.h"
 #include "platform/json.h"
@@ skipping 777 matching lines @@
       trace_buffer_(NULL),
       profiler_data_(NULL),
       tag_table_(GrowableObjectArray::null()),
       collected_closures_(GrowableObjectArray::null()),
       deoptimized_code_array_(GrowableObjectArray::null()),
       background_compilation_queue_(GrowableObjectArray::null()),
       pending_service_extension_calls_(GrowableObjectArray::null()),
       registered_service_extension_handlers_(GrowableObjectArray::null()),
       metrics_list_head_(NULL),
       compilation_allowed_(true),
-      cha_(NULL),
       next_(NULL),
       pause_loop_monitor_(NULL) {
   flags_.CopyFrom(api_flags);
   Thread::Current()->set_vm_tag(VMTag::kEmbedderTagId);
   set_user_tag(UserTags::kDefaultUserTag);
 }
 
 #undef REUSABLE_HANDLE_SCOPE_INIT
 #undef REUSABLE_HANDLE_INITIALIZERS
 
@@ skipping 1812 matching lines @@
                            serialized_message_, serialized_message_len_);
 }
 
 
 void IsolateSpawnState::Cleanup() {
   SwitchIsolateScope switch_scope(I);
   Dart::ShutdownIsolate();
 }
 
 }  // namespace dart