Add the ability to run test suites in parallel.

lib/src/runner/browser/compiler_pool.dart

 // Copyright (c) 2015, 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.
 
 library test.util.compiler_pool;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:io';
 
@@ skipping 23 matching lines @@
   /// have already exited; they're kept around so that their output can be
   /// emitted once they become visible.
   final _compilers = new Queue<_Compiler>();
 
   /// Whether [close] has been called.
   bool get _closed => _closeCompleter != null;
 
   /// The completer for the [Future] returned by [close].
   Completer _closeCompleter;
 
-  /// Creates a compiler pool that runs up to [parallel] instances of `dart2js`
-  /// at once.
+  /// Creates a compiler pool that runs up to [concurrency] instances of
+  /// `dart2js` at once.
   ///
-  /// If [parallel] isn't provided, it defaults to 4.
+  /// If [concurrency] isn't provided, it defaults to 4.
   ///
   /// If [color] is true, `dart2js` will be run with colors enabled.
-  CompilerPool({int parallel, bool color: false})
-      : _pool = new Pool(parallel == null ? 4 : parallel),
+  CompilerPool({int concurrency, bool color: false})
+      : _pool = new Pool(concurrency == null ? 4 : concurrency),
         _color = color;
 
   /// Compile the Dart code at [dartPath] to [jsPath].
   ///
   /// This wraps the Dart code in the standard browser-testing wrapper. If
   /// [packageRoot] is provided, it's used as the package root for the
   /// compilation.
   ///
   /// The returned [Future] will complete once the `dart2js` process completes
   /// *and* all its output has been printed to the command line.
@@ skipping 99 matching lines @@
   /// The underlying process.
   final Process process;
 
   /// A future that will complete once this instance has finished running and
   /// all its output has been printed.
   Future get onDone => onDoneCompleter.future;
   final onDoneCompleter = new Completer();
 
   _Compiler(this.path, this.process);
 }