Fix more strong mode errors and warnings.

lib/src/io.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// Helper functionality to make working with IO easier.
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io';
 
@@ skipping 665 matching lines @@
 /// Spawns and runs the process located at [executable], passing in [args].
 ///
 /// Returns a [Future] that will complete with the results of the process after
 /// it has ended.
 ///
 /// The spawned process will inherit its parent's environment variables. If
 /// [environment] is provided, that will be used to augment (not replace) the
 /// the inherited variables.
 Future<PubProcessResult> runProcess(String executable, List<String> args,
     {workingDir, Map<String, String> environment, bool runInShell: false}) {
-  return _descriptorPool.withResource(() async {
+  return _descriptorPool.withResource/*<Future<PubProcessResult>>*/(() async {
     var result = await _doProcess(Process.run, executable, args,
         workingDir: workingDir,
         environment: environment,
         runInShell: runInShell);
 
     var pubResult = new PubProcessResult(
         result.stdout, result.stderr, result.exitCode);
     log.processResult(executable, pubResult);
     return pubResult;
   });
@@ skipping 385 matching lines @@
 
   // TODO(rnystrom): Remove this and change to returning one string.
   static List<String> _toLines(String output) {
     var lines = splitLines(output);
     if (!lines.isEmpty && lines.last == "") lines.removeLast();
     return lines;
   }
 
   bool get success => exitCode == exit_codes.SUCCESS;
 }