Make a bunch of stuff in pub synchronous.

utils/pub/command_lish.dart

Index: utils/pub/command_lish.dart
diff --git a/utils/pub/command_lish.dart b/utils/pub/command_lish.dart
index 1e5673da28f9b82319315a44d9776cff89cd891e..4a370d7d67a1815dce0c76525bb35b7b3c167b9e 100644
--- a/utils/pub/command_lish.dart
+++ b/utils/pub/command_lish.dart
@@ -109,7 +109,7 @@ class LishCommand extends PubCommand {
 
   /// The basenames of directories that are automatically excluded from
   /// archives.
-  final _BLACKLISTED_DIRECTORIES = const ['packages'];
+  final _BLACKLISTED_DIRS = const ['packages'];
 
   /// Returns a list of files that should be included in the published package.
   /// If this is a Git repository, this will respect .gitignore; otherwise, it
@@ -117,11 +117,8 @@ class LishCommand extends PubCommand {
   Future<List<String>> get _filesToPublish {
     var rootDir = entrypoint.root.dir;
 
-    return Future.wait([
-      dirExists(join(rootDir, '.git')),
-      git.isInstalled
-    ]).then((results) {
-      if (results[0] && results[1]) {
+    return git.isInstalled.then((gitInstalled) {
+      if (dirExists(join(rootDir, '.git')) && gitInstalled) {
         // List all files that aren't gitignored, including those not checked
         // in to Git.
         return git.run(["ls-files", "--cached", "--others",
@@ -129,27 +126,17 @@ class LishCommand extends PubCommand {
       }
 
       return listDir(rootDir, recursive: true).then((entries) {
-        return Future.wait(entries.map((entry) {
-          return fileExists(entry).then((isFile) {
-            // Skip directories.
-            if (!isFile) return null;
-
-            // TODO(rnystrom): Making these relative will break archive
-            // creation if the cwd is ever *not* the package root directory.
-            // Should instead only make these relative right before generating
-            // the tree display (which is what really needs them to be).
-            // Make it relative to the package root.
-            return relativeTo(entry, rootDir);
-          });
-        }));
+        return entries
+            .where(fileExists) // Skip directories.
+            .map((entry) => relativeTo(entry, rootDir));
       });
-    }).then((files) => files.where((file) {
-      if (file == null || _BLACKLISTED_FILES.contains(basename(file))) {
-        return false;
-      }
+    }).then((files) => files.where(_shouldPublish).toList());
+  }
 
-      return !splitPath(file).any(_BLACKLISTED_DIRECTORIES.contains);
-    }).toList());
+  /// Returns `true` if [file] should be published.
+  bool _shouldPublish(String file) {
+    if (_BLACKLISTED_FILES.contains(basename(file))) return false;
+    return !splitPath(file).any(_BLACKLISTED_DIRS.contains);
   }
 
   /// Returns the value associated with [key] in [map]. Throws a user-friendly