Thread/Isolate refactoring: new(Isolate) -> new(Zone)

runtime/lib/isolate.cc

 // 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.
 
 #include "platform/assert.h"
 #include "vm/bootstrap_natives.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
@@ skipping 247 matching lines @@
       Library::Handle(arguments->isolate()->object_store()->root_library());
   if (!CanonicalizeUri(arguments->isolate(), root_lib, uri,
                        &canonical_uri, &error)) {
     const String& msg = String::Handle(String::New(error));
     ThrowIsolateSpawnException(msg);
   }
 
   char* utf8_package_root = NULL;
   if (!package_root.IsNull()) {
     const intptr_t len = Utf8::Length(package_root);
-    Zone* zone = isolate->current_zone();
     utf8_package_root = zone->Alloc<char>(len + 1);
     package_root.ToUTF8(reinterpret_cast<uint8_t*>(utf8_package_root), len);
     utf8_package_root[len] = '\0';
   }
 
   Spawn(isolate, new IsolateSpawnState(port.Id(),
                                        canonical_uri,
                                        utf8_package_root,
                                        args,
                                        message,
@@ skipping 24 matching lines @@
   MessageWriter writer(&data, &allocator, false);
   writer.WriteMessage(msg);
 
   PortMap::PostMessage(new Message(port.Id(),
                                    data, writer.BytesWritten(),
                                    Message::kOOBPriority));
   return Object::null();
 }
 
 }  // namespace dart