Fix pub errorgroup and analyzer errors.

sdk/lib/_internal/pub/lib/src/error_group.dart

Index: sdk/lib/_internal/pub/lib/src/error_group.dart
diff --git a/sdk/lib/_internal/pub/lib/src/error_group.dart b/sdk/lib/_internal/pub/lib/src/error_group.dart
index cc7b0071b3d82b4eda21a1fe63faecee17ea10ed..b49b45a3702b3ffbdaeeec7f15140c071bcf1279 100644
--- a/sdk/lib/_internal/pub/lib/src/error_group.dart
+++ b/sdk/lib/_internal/pub/lib/src/error_group.dart
@@ -225,6 +225,10 @@ class _ErrorGroupStream extends Stream {
   /// The underlying [StreamController] for [this].
   final StreamController _controller;
 
+  /// The controller's [Stream]. May be different than `_controller.stream` if
+  /// the wrapped stream is a broadcasting stream.
+  Stream _stream;
+
   /// The [StreamSubscription] that connects the wrapped [Stream] to
   /// [_controller].
   StreamSubscription _subscription;
@@ -235,9 +239,12 @@ class _ErrorGroupStream extends Stream {
   /// Creates a new [_ErrorGroupFuture] that's a child of [_group] and wraps
   /// [inner].
   _ErrorGroupStream(this._group, Stream inner)
-    : _controller =
-          inner.isBroadcast ? new StreamController.broadcast(sync: true)
-                            : new StreamController(sync: true) {
+    : _controller = new StreamController(sync: true) {
+    // Use old-style asBroadcastStream behavior - cancel source _subscription
+    // the first time the stream has no listeners.
+    _stream = inner.isBroadcast
+        ? _controller.stream.asBroadcastStream(onCancel: (sub) => sub.cancel())
+        : _controller.stream;
     _subscription = inner.listen((v) {
       _controller.add(v);
     }, onError: (e) {
@@ -252,7 +259,7 @@ class _ErrorGroupStream extends Stream {
   StreamSubscription listen(void onData(value),
       {void onError(var error), void onDone(),
        bool cancelOnError}) {
-    return _controller.stream.listen(onData,
+    return _stream.listen(onData,
         onError: onError,
         onDone: onDone,
         cancelOnError: true);