Add bazel worker support to the dev compiler.

bin/dartdevc.dart

Index: bin/dartdevc.dart
diff --git a/bin/dartdevc.dart b/bin/dartdevc.dart
index 6be7a969f9cb54b4436749b15489cd80169cf8f8..096b7fe5fd25407cab5da0faa51e6dd7dfbcf55c 100755
--- a/bin/dartdevc.dart
+++ b/bin/dartdevc.dart
@@ -40,6 +40,8 @@ import 'package:args/command_runner.dart';
 import 'package:dev_compiler/src/compiler/command.dart';
 
 main(List<String> args) async {
+  args = _preprocessArgs(args);
+
   var runner = new CommandRunner('dartdevc', 'Dart Development Compiler');
   runner.addCommand(new CompileCommand());
   try {
@@ -76,3 +78,14 @@ main(List<String> args) async {
     print("```");
   }
 }
+
+/// If the final arg is `@file_path` then read in all the lines of that file
+/// and add those as args.

[Jennifer Messerly, 2016/04/14 21:02:14]

add a comment that this is required by Bazel workers?

[jakemac, 2016/04/14 21:48:25]

Done.

+List<String> _preprocessArgs(List<String> args) {
+  if (args.last.startsWith('@')) {
+    return new List.from(args)
+      ..addAll(new File(args.last.substring(1)).readAsLinesSync());
+  } else {
+    return args;
+  }
+}