Support configuring dart2js from the pubspec.

sdk/lib/_internal/pub/test/transformer/dart2js/supports_valid_options_test.dart

Index: sdk/lib/_internal/pub/test/transformer/dart2js/supports_valid_options_test.dart
diff --git a/sdk/lib/_internal/pub/test/transformer/dart2js/supports_valid_options_test.dart b/sdk/lib/_internal/pub/test/transformer/dart2js/supports_valid_options_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..ffdda137e578cc12ba23eff7a3a8eedc92309232
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+++ b/sdk/lib/_internal/pub/test/transformer/dart2js/supports_valid_options_test.dart
@@ -0,0 +1,46 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS d.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 pub_tests;
+
+import 'package:scheduled_test/scheduled_test.dart';
+
+import '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+import '../../serve/utils.dart';
+
+main() {
+  initConfig();
+
+  integration("supports most dart2js command-line options", () {
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "transformers": [{
+          "\$dart2js": {
+            "commandLineOptions": ["--enable-diagnostic-colors"],
+            "checked": true,
+            "minify": true,
+            "verbose": true,
+            "environment": {"name": "value"},
+            "analyzeAll": true,
+            "suppressWarnings": true,
+            "suppressHints": true,
+            "terse": true
+          }
+        }]
+      }),
+      d.dir("lib", [d.dir("src", [
+        d.file("transformer.dart", REWRITE_TRANSFORMER)
+      ])])
+    ]).create();
+
+    createLockFile('myapp', pkg: ['barback']);
+
+    // None of these options should be rejected, either by pub or by dart2js.
+    pubServe();
+    requestShouldSucceed("main.dart.js", isNot(isEmpty));
+    endPubServe();
+  });
+}