Make Stream.where, etc., be documented as inheriting broadcast state.

tests/lib/async/stream_timeout_test.dart

Index: tests/lib/async/stream_timeout_test.dart
diff --git a/tests/lib/async/stream_timeout_test.dart b/tests/lib/async/stream_timeout_test.dart
index eac7100511c5a07917bbe0a5e726c8d4a210f0c0..e0854960d2564c22abed53dcaa8ae59878eb6dc8 100644
--- a/tests/lib/async/stream_timeout_test.dart
+++ b/tests/lib/async/stream_timeout_test.dart
@@ -67,7 +67,7 @@ main() {
   test("broadcast stream timeout",  () {
     StreamController c = new StreamController.broadcast();
     Stream tos = c.stream.timeout(ms5);
-    expect(tos.isBroadcast, false);
+    expect(tos.isBroadcast, true);
     tos.handleError(expectAsync((e, s) {
       expect(e, new isInstanceOf<TimeoutException>());
       expect(s, null);
@@ -77,7 +77,7 @@ main() {
   test("asBroadcast stream timeout",  () {
     StreamController c = new StreamController.broadcast();
     Stream tos = c.stream.asBroadcastStream().timeout(ms5);
-    expect(tos.isBroadcast, false);
+    expect(tos.isBroadcast, true);
     tos.handleError(expectAsync((e, s) {
       expect(e, new isInstanceOf<TimeoutException>());
       expect(s, null);