fixes #610, incorrect help output

bin/dartdevc.dart

Index: bin/dartdevc.dart
diff --git a/bin/dartdevc.dart b/bin/dartdevc.dart
index 98c3e450a2eb691b46021867f761740fa085c7f5..e6ca6a7f64d0cd9b5378f49233df31f38121b916 100755
--- a/bin/dartdevc.dart
+++ b/bin/dartdevc.dart
@@ -38,7 +38,6 @@
 import 'dart:async';
 import 'dart:io';
 import 'package:analyzer/src/generated/engine.dart' show AnalysisEngine;
-import 'package:args/command_runner.dart';
 import 'package:bazel_worker/bazel_worker.dart';
 import 'package:dev_compiler/src/compiler/command.dart';
 
@@ -49,28 +48,10 @@ Future main(List<String> args) async {
   if (args.contains('--persistent_worker')) {
     new _CompilerWorker(args..remove('--persistent_worker')).run();
   } else {
-    exitCode = await _runCommand(args);
+    exitCode = compile(args);
   }
 }
 
-/// Runs a single compile command, and returns an exit code.
-Future<int> _runCommand(List<String> args,
-    {MessageHandler messageHandler}) async {
-  try {
-    if (args.isEmpty || args.first != 'compile' && args.first != 'help') {
-      // TODO(jmesserly): we should deprecate the commands. For now they are
-      // still supported for backwards compatibility.
-      args.insert(0, 'compile');
-    }
-    var runner = new CommandRunner('dartdevc', 'Dart Development Compiler');
-    runner.addCommand(new CompileCommand(messageHandler: messageHandler));
-    await runner.run(args);
-  } catch (e, s) {
-    return _handleError(e, s, args, messageHandler: messageHandler);
-  }
-  return EXIT_CODE_OK;
-}
-
 /// Runs the compiler worker loop.
 class _CompilerWorker extends AsyncWorkerLoop {
   /// The original args supplied to the executable.
@@ -83,7 +64,7 @@ class _CompilerWorker extends AsyncWorkerLoop {
     var args = _startupArgs.toList()..addAll(request.arguments);
 
     var output = new StringBuffer();
-    var exitCode = await _runCommand(args, messageHandler: output.writeln);
+    var exitCode = compile(args, printFn: output.writeln);
     AnalysisEngine.instance.clearCaches();
     return new WorkResponse()
       ..exitCode = exitCode
@@ -91,48 +72,6 @@ class _CompilerWorker extends AsyncWorkerLoop {
   }
 }
 
-/// Handles [error] in a uniform fashion. Returns the proper exit code and calls
-/// [messageHandler] with messages.
-int _handleError(dynamic error, dynamic stackTrace, List<String> args,
-    {MessageHandler messageHandler}) {
-  messageHandler ??= print;
-
-  if (error is UsageException) {
-    // Incorrect usage, input file not found, etc.
-    messageHandler(error);
-    return 64;
-  } else if (error is CompileErrorException) {
-    // Code has error(s) and failed to compile.
-    messageHandler(error);
-    return 1;
-  } else {
-    // Anything else is likely a compiler bug.
-    //
-    // --unsafe-force-compile is a bit of a grey area, but it's nice not to
-    // crash while compiling
-    // (of course, output code may crash, if it had errors).
-    //
-    messageHandler("");
-    messageHandler("We're sorry, you've found a bug in our compiler.");
-    messageHandler("You can report this bug at:");
-    messageHandler("    https://github.com/dart-lang/dev_compiler/issues");
-    messageHandler("");
-    messageHandler(
-        "Please include the information below in your report, along with");
-    messageHandler(
-        "any other information that may help us track it down. Thanks!");
-    messageHandler("");
-    messageHandler("    dartdevc arguments: " + args.join(' '));
-    messageHandler("    dart --version: ${Platform.version}");
-    messageHandler("");
-    messageHandler("```");
-    messageHandler(error);
-    messageHandler(stackTrace);
-    messageHandler("```");
-    return 70;
-  }
-}
-
 /// Always returns a new modifiable list.
 ///
 /// If the final arg is `@file_path` then read in all the lines of that file