Create _RootZone and _RootSpecification.

sdk/lib/async/zone.dart

Index: sdk/lib/async/zone.dart
diff --git a/sdk/lib/async/zone.dart b/sdk/lib/async/zone.dart
index 80184c2e75e67f00ef01e7c42e0f269589dbd582..be8e11439fb49e6fbdc42e9f80e0ec4b97daa65d 100644
--- a/sdk/lib/async/zone.dart
+++ b/sdk/lib/async/zone.dart
@@ -756,22 +756,80 @@ Zone _rootFork(Zone self, ZoneDelegate parent, Zone zone,
   return new _CustomizedZone(zone, specification, copiedMap);
 }
 
-const _ROOT_SPECIFICATION = const ZoneSpecification(
-  handleUncaughtError: _rootHandleUncaughtError,
-  run: _rootRun,
-  runUnary: _rootRunUnary,
-  runBinary: _rootRunBinary,
-  registerCallback: _rootRegisterCallback,
-  registerUnaryCallback: _rootRegisterUnaryCallback,
-  registerBinaryCallback: _rootRegisterBinaryCallback,
-  scheduleMicrotask: _rootScheduleMicrotask,
-  createTimer: _rootCreateTimer,
-  createPeriodicTimer: _rootCreatePeriodicTimer,
-  fork: _rootFork
-);
-
-const _ROOT_ZONE =
-    const _CustomizedZone(null, _ROOT_SPECIFICATION, const <Symbol, dynamic>{});
+class _RootZoneSpecification implements ZoneSpecification {
+  const _RootZoneSpecification();
+
+  HandleUncaughtErrorHandler get handleUncaughtError =>
+      _rootHandleUncaughtError;
+  RunHandler get run => _rootRun;
+  RunUnaryHandler get runUnary => _rootRunUnary;
+  RunBinaryHandler get runBinary => _rootRunBinary;
+  RegisterCallbackHandler get registerCallback => _rootRegisterCallback;
+  RegisterUnaryCallbackHandler get registerUnaryCallback =>
+      _rootRegisterUnaryCallback;
+  RegisterBinaryCallbackHandler get registerBinaryCallback =>
+      _rootRegisterBinaryCallback;
+  ScheduleMicrotaskHandler get scheduleMicrotask => _rootScheduleMicrotask;
+  @deprecated
+  RunAsyncHandler get runAsync => null;
+  CreateTimerHandler get createTimer => _rootCreateTimer;
+  CreatePeriodicTimerHandler get createPeriodicTimer =>
+      _rootCreatePeriodicTimer;
+  ForkHandler get fork => _rootFork;
+}
+
+class _RootZone extends _CustomizedZone {
+  const _RootZone()
+      : super(null, const _RootZoneSpecification(), const <Symbol, dynamic>{});

[Lasse Reichstein Nielsen, 2013/10/15 12:04:07]

Can you replace the map with null, since it is never read?

You override ... 15 out of 22 methods. 
Are you sure it wouldn't be easier to implement Zone and do the remaining five,
instead of passing irrelevant data to the super constructor.

[floitsch, 2013/10/15 13:06:07]

Done.

+
+  Zone get _errorZone => this;
+
+  bool inSameErrorZone(Zone otherZone) => otherZone._errorZone == this;
+
+  operator [](Symbol key) => null;
+
+  // Methods that can be customized by the zone specification.
+
+  dynamic handleUncaughtError(error, StackTrace stackTrace) =>
+      _rootHandleUncaughtError(this, null, this, error, stackTrace);
+
+  Zone fork({ZoneSpecification specification, Map zoneValues}) =>
+      _rootFork(this, null, this, specification, zoneValues);
+
+  dynamic run(f()) => _rootRun(this, null, this, f);
+
+  dynamic runUnary(f(arg), arg) => _rootRunUnary(this, null, this, f, arg);
+
+  dynamic runBinary(f(arg1, arg2), arg1, arg2) =>
+      _rootRunBinary(this, null, this, f, arg1, arg2);
+
+  ZoneCallback registerCallback(f()) =>
+      _rootRegisterCallback(this, null, this, f);
+
+  ZoneUnaryCallback registerUnaryCallback(f(arg)) =>
+      _rootRegisterUnaryCallback(this, null, this, f);
+
+  ZoneBinaryCallback registerBinaryCallback(f(arg1, arg2)) =>
+      _rootRegisterBinaryCallback(this, null, this, f);
+
+  void scheduleMicrotask(void f()) {
+    _rootScheduleMicrotask(this, null, this, f);
+  }
+
+  @deprecated
+  void runAsync(void f()) {
+    scheduleMicrotask(f);
+  }
+
+  Timer createTimer(Duration duration, void f()) =>
+      _rootCreateTimer(this, null, this, duration, f);
+
+  Timer createPeriodicTimer(Duration duration, void f(Timer timer)) =>
+      _rootCreatePeriodicTimer(this, null, this, duration, f);
+}
+
+const _ROOT_SPECIFICATION = const _RootZoneSpecification();
+const _ROOT_ZONE = const _RootZone();
 
 
 /**