Update tonic for VM roll

dart_vm.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "tonic/dart_vm.h"
 
 #include "base/logging.h"
 #include "tonic/dart_debugger.h"
 
 namespace tonic {
 
 static char* dart_vm_error_ = NULL;
 
 DartVM::Config::Config() {
   vm_isolate_snapshot = nullptr;
   instructions_snapshot = nullptr;
   data_snapshot = nullptr;
   create = nullptr;
   interrupt = nullptr;
   unhandled_exception = nullptr;
   shutdown = nullptr;
+  thread_exit = nullptr;
   file_open = nullptr;
   file_read = nullptr;
   file_write = nullptr;
   file_close = nullptr;
   entropy_source = nullptr;
   get_service_assets = nullptr;
 }
 
 bool DartVM::Initialize(const Config& config,
                         const std::vector<const char*>& flags) {
   CHECK(dart_vm_error_ == NULL);
 
   // Set the flags before calling Dart_Initialize.
   if (!Dart_SetVMFlags(flags.size(), const_cast<const char**>(flags.data()))) {
     dart_vm_error_ = strdup("Error in Dart_SetVMFlags.");
     LOG(ERROR) << "Dart_SetVMFlags: " << dart_vm_error_;
     return false;
   }
 
   // Initialize debugger before calling Dart_Initialize.
   DartDebugger::InitDebugger();
 
   dart_vm_error_ = Dart_Initialize(config.vm_isolate_snapshot,
                                    config.instructions_snapshot,
                                    config.data_snapshot,
                                    config.create,
                                    config.interrupt,
                                    config.unhandled_exception,
                                    config.shutdown,
+                                   config.thread_exit,
                                    config.file_open,
                                    config.file_read,
                                    config.file_write,
                                    config.file_close,
                                    config.entropy_source,
                                    config.get_service_assets);
   if (dart_vm_error_ != NULL) {
     LOG(ERROR) << "Dart_Initialize: " << dart_vm_error_;
   }
   return dart_vm_error_ == NULL;
 }
 
 bool DartVM::Cleanup() {
   CHECK(dart_vm_error_ == NULL);
   dart_vm_error_ = Dart_Cleanup();
   if (dart_vm_error_ != NULL) {
     LOG(ERROR) << "Dart_Cleanup: " << dart_vm_error_;
   }
   return dart_vm_error_ == NULL;
 }
 
 const char* DartVM::error() {
   CHECK(dart_vm_error_ != NULL);
   return dart_vm_error_;
 }
 
 }  // namespace tonic