Don't test for file differences in the polling watcher.

Don't test for file differences in the polling watcher.

The non-polling forms don't do this, so this makes the polling
style behave the same. It also has two important benefits:

1. On Windows, this avoids opening the files being watched.
   Since opening a file prevents it from being deleted on
   Windows, this causes the watcher to interfere with the
   files and leads to some flaky tests and buggy user
   behavior.

2. It saves some time and memory since we don't need to store
   the SHA1 for every file being watched.

BUG=http://dartbug.com/13026, http://dartbug.com/15431
R=nweiz@google.com

Committed: https://code.google.com/p/dart/source/detail?r=31574

[nweiz, 2014-01-06 23:51:52]

lgtm

https://codereview.chromium.org/122573003/diff/40001/pkg/watcher/test/directo...
File pkg/watcher/test/directory_watcher/polling_test.dart (left):

https://codereview.chromium.org/122573003/diff/40001/pkg/watcher/test/directo...
pkg/watcher/test/directory_watcher/polling_test.dart:29: });
There's a variant of this test in the Linux and Mac directory watcher tests that
says "notifies even if the file contents are unchanged". That variant should be
moved into the shared.dart.

[Bob Nystrom, 2014-01-07 21:09:04]

https://codereview.chromium.org/122573003/diff/40001/pkg/watcher/test/directo...
File pkg/watcher/test/directory_watcher/polling_test.dart (left):

https://codereview.chromium.org/122573003/diff/40001/pkg/watcher/test/directo...
pkg/watcher/test/directory_watcher/polling_test.dart:29: });
On 2014/01/06 23:51:52, nweiz wrote:
> There's a variant of this test in the Linux and Mac directory watcher tests
that
> says "notifies even if the file contents are unchanged". That variant should
be
> moved into the shared.dart.

Done.

[Bob Nystrom, 2014-01-07 21:10:04]

Committed patchset #3 manually as r31574 (presubmit successful).