Roll Observatory packages and add a roll script

which/lib/which.dart

Index: which/lib/which.dart
diff --git a/which/lib/which.dart b/which/lib/which.dart
deleted file mode 100755
index c9047a3c11541130b6bbcac7650da65c3a474771..0000000000000000000000000000000000000000
--- a/which/lib/which.dart
+++ /dev/null
@@ -1,29 +0,0 @@
-
-library which;
-
-import 'dart:async';
-import 'dart:io';
-
-import 'src/candidate_paths.dart';
-import 'src/is_executable.dart';
-import 'src/which_impl.dart' as impl;
-
-/// Returns a future for the first [command] executable in the `PATH`.
-///
-/// If [command] is not found, [orElse] is called, which defaults to throwing.
-Future<String> which(String command, { orElse() }) => new Future(() => impl.which(
-    command,
-    getRealCandidatePaths(command),
-    Platform.isWindows,
-    (path, isWindows) => isExecutable(path, isWindows, FileStat.stat),
-    orElse));
-
-/// Returns the first [command] executable in the `PATH`.
-///
-/// If [command] is not found, [orElse] is called, which defaults to throwing.
-String whichSync(String command, { orElse() }) => impl.whichSync(
-    command,
-    getRealCandidatePaths(command),
-    Platform.isWindows,
-    (path, isWindows) => isExecutableSync(path, isWindows, FileStat.statSync),
-    orElse);