emit interfaces before use

lib/runtime/dart/isolate.js

Index: lib/runtime/dart/isolate.js
diff --git a/lib/runtime/dart/isolate.js b/lib/runtime/dart/isolate.js
index 00a3ec98fa92ad16f6810616cd11a979344f8555..ab563a67358ebc80eec27b0616fcc4e89f1014e7 100644
--- a/lib/runtime/dart/isolate.js
+++ b/lib/runtime/dart/isolate.js
@@ -155,19 +155,23 @@ var isolate;
       return _isolate_helper.IsolateNatives.currentIsolate;
     }
   });
-  class SendPort extends core.Object {
-  }
+  class SendPort extends core.Object {}
   SendPort[dart.implements] = [Capability];
-  class ReceivePort extends core.Object {
-    ReceivePort() {
-      return new _isolate_helper.ReceivePortImpl();
-    }
-    fromRawReceivePort(rawPort) {
-      return new _isolate_helper.ReceivePortImpl.fromRawReceivePort(rawPort);
+  dart.defineLazyClass(exports, {
+    get ReceivePort() {
+      class ReceivePort extends core.Object {
+        ReceivePort() {
+          return new _isolate_helper.ReceivePortImpl();
+        }
+        fromRawReceivePort(rawPort) {
+          return new _isolate_helper.ReceivePortImpl.fromRawReceivePort(rawPort);
+        }
+      }
+      ReceivePort[dart.implements] = [async.Stream];
+      dart.defineNamedConstructor(ReceivePort, 'fromRawReceivePort');
+      return ReceivePort;
     }
-  }
-  ReceivePort[dart.implements] = [async.Stream];
-  dart.defineNamedConstructor(ReceivePort, 'fromRawReceivePort');
+  });
   class RawReceivePort extends core.Object {
     RawReceivePort(handler) {
       if (handler === void 0)
@@ -212,7 +216,6 @@ var isolate;
   exports.IsolateSpawnException = IsolateSpawnException;
   exports.Isolate = Isolate;
   exports.SendPort = SendPort;
-  exports.ReceivePort = ReceivePort;
   exports.RawReceivePort = RawReceivePort;
   exports.RemoteError = RemoteError;
 })(isolate || (isolate = {}));