fix webui for sdk 0.8.7

lib/src/utils_observe.dart

Index: lib/src/utils_observe.dart
diff --git a/lib/src/utils_observe.dart b/lib/src/utils_observe.dart
index c6c73b54feec2f29c2c9d6e7c1d2774ad2c38f88..670dda39a7f51214fa0b001b8dae219816d4dee4 100644
--- a/lib/src/utils_observe.dart
+++ b/lib/src/utils_observe.dart
@@ -4,8 +4,8 @@
 
 library web_ui.src.utils_observe;
 
+import 'dart:async';
 import 'dart:collection';
-import 'dart:isolate';
 
 // TODO(jmesserly): helpers to combine hash codes. Reuse these from somewhere.
 hash2(x, y) => x.hashCode * 31 + y.hashCode;
@@ -14,23 +14,6 @@ hash3(x, y, z) => hash2(hash2(x, y), z);
 
 hash4(w, x, y, z) => hash2(hash2(w, x), hash2(y, z));
 
-// TODO(jmesserly): replace with something in dart:async, as long as it is based
-// on window.setImmediate/mutation observers/postMessage and not setTimeout(0)
-// Maybe we can use Future.value? We need it to be fast (next microtask)
-// like this though: http://dartbug.com/8757.
-/**
- * Adds an event to call [callback], so the event loop will call this after the
- * current stack has unwound.
- */
-void setImmediate(void callback()) {
-  var port = new ReceivePort();
-  port.receive((msg, sendPort) {
-    port.close();
-    callback();
-  });
-  port.toSendPort().send(null);
-}
-
 class Arrays {
   static void copy(List src, int srcStart,
                    List dst, int dstStart, int count) {