Add unhandledExceptionCallback to streamSpawnFunction.

sdk/lib/isolate/isolate_stream.dart

Index: sdk/lib/isolate/isolate_stream.dart
diff --git a/sdk/lib/isolate/isolate_stream.dart b/sdk/lib/isolate/isolate_stream.dart
index 4cb39f1aa9402750c335c057dc62676517daeac3..05ea5a0d7503f086518170fe669fb1eda7f77ea3 100644
--- a/sdk/lib/isolate/isolate_stream.dart
+++ b/sdk/lib/isolate/isolate_stream.dart
@@ -198,8 +198,11 @@ class IsolateSink extends StreamSink<dynamic> {
  *
  * See comments at the top of this library for more details.
  */
-IsolateSink streamSpawnFunction(void topLevelFunction()) {
-  SendPort sendPort = spawnFunction(topLevelFunction);
+IsolateSink streamSpawnFunction(
+    void topLevelFunction(),
+    [bool unhandledExceptionCallback(IsolateUnhandledException e)]) {
+  SendPort sendPort = spawnFunction(topLevelFunction,
+                                    unhandledExceptionCallback);
   return new IsolateSink._fromPort(sendPort);
 }