Stop expecting errors when pausing, resuming or canceling a canceled stream.

tests/html/streams_test.dart

Index: tests/html/streams_test.dart
diff --git a/tests/html/streams_test.dart b/tests/html/streams_test.dart
index 843e1c7916f7c62cc138ac61e9305dc70d219877..266edc8146d35799b98366f3f019ee8edb94f314 100644
--- a/tests/html/streams_test.dart
+++ b/tests/html/streams_test.dart
@@ -87,13 +87,10 @@ main() {
       subscription.onData((_) {});
     }, throws);
 
-    expect(() {
-      subscription.pause();
-    }, throws);
-
-    expect(() {
-      subscription.resume();
-    }, throws);
+    // Calling these after a cancel does nothing.
+    subscription.cancel();
+    subscription.pause();
+    subscription.resume();
   });
 
   test('pause/resume', () {
@@ -131,10 +128,8 @@ main() {
     helper.pulse();
     expect(callCount, 3);
 
-    // Not paused.
-    expect(() {
-      subscription.resume();
-    }, throws);
+    // Not paused, but resuming once too often is ok.
+    subscription.resume();
   });
 
   test('onData', () {