Use stream matchers to unflake the mac OS watcher tests.

pkg/watcher/test/directory_watcher/mac_os_test.dart

Index: pkg/watcher/test/directory_watcher/mac_os_test.dart
diff --git a/pkg/watcher/test/directory_watcher/mac_os_test.dart b/pkg/watcher/test/directory_watcher/mac_os_test.dart
index 077787a29e6c624bb364fe556a6384af7ef6d18c..216f2e0e05ea971db3204e9d292d6f25f1efd91f 100644
--- a/pkg/watcher/test/directory_watcher/mac_os_test.dart
+++ b/pkg/watcher/test/directory_watcher/mac_os_test.dart
@@ -38,6 +38,9 @@ main() {
 
   test('emits events for many nested files moved out then immediately back in',
       () {
+    // TODO(nweiz): re-enable this when issue 16003 is fixed.
+    return;

[Bob Nystrom, 2014/01/09 22:49:20]

I think this generates an unreachable code warning in the Editor. Also, this
will still print the test in the output I'd just comment out the whole test.

[nweiz, 2014/01/10 01:05:31]

Done.

+
     withPermutations((i, j, k) =>
         writeFile("dir/sub/sub-$i/sub-$j/file-$k.txt"));
 
@@ -46,14 +49,15 @@ main() {
     renameDir("dir/sub", "sub");
     renameDir("sub", "dir/sub");
 
-    inAnyOrder(() {
-      withPermutations((i, j, k) =>
-          expectRemoveEvent("dir/sub/sub-$i/sub-$j/file-$k.txt"));
-    });
+    allowEither(() {
+      inAnyOrder(withPermutations((i, j, k) =>
+          isRemoveEvent("dir/sub/sub-$i/sub-$j/file-$k.txt")));
 
-    inAnyOrder(() {
-      withPermutations((i, j, k) =>
-          expectAddEvent("dir/sub/sub-$i/sub-$j/file-$k.txt"));
+      inAnyOrder(withPermutations((i, j, k) =>
+          isAddEvent("dir/sub/sub-$i/sub-$j/file-$k.txt")));
+    }, () {
+      inAnyOrder(withPermutations((i, j, k) =>
+          isModifyEvent("dir/sub/sub-$i/sub-$j/file-$k.txt")));
     });
   });
 }