Allow user to specify mode for pub build/serve.

sdk/lib/_internal/pub/test/build/includes_dart_files_in_debug_mode_test.dart

Index: sdk/lib/_internal/pub/test/build/includes_dart_files_in_debug_mode_test.dart
diff --git a/sdk/lib/_internal/pub/test/build/ignores_non_entrypoint_dart_files_test.dart b/sdk/lib/_internal/pub/test/build/includes_dart_files_in_debug_mode_test.dart
similarity index 68%
copy from sdk/lib/_internal/pub/test/build/ignores_non_entrypoint_dart_files_test.dart
copy to sdk/lib/_internal/pub/test/build/includes_dart_files_in_debug_mode_test.dart
index 94eb21b304b58cff546e2309d28e21738f994dc9..96f3cd06eb8e01421673b30f4300dde3d8f5af45 100644
--- a/sdk/lib/_internal/pub/test/build/ignores_non_entrypoint_dart_files_test.dart
+++ b/sdk/lib/_internal/pub/test/build/includes_dart_files_in_debug_mode_test.dart
@@ -2,7 +2,7 @@
 // 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.
 
-import 'package:path/path.dart' as path;
+import 'package:scheduled_test/scheduled_test.dart';
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
@@ -10,7 +10,7 @@ import '../test_pub.dart';
 main() {
   initConfig();
 
-  integration("ignores non-entrypoint Dart files", () {
+  integration("includes Dart files in debug mode", () {
     d.dir(appPath, [
       d.appPubspec(),
       d.dir('web', [
@@ -21,20 +21,20 @@ main() {
       ])
     ]).create();
 
-    schedulePub(args: ["build"],
-        output: new RegExp(r"Built 0 files!"),
+    schedulePub(args: ["build", "--mode", "debug"],
+        output: new RegExp(r"Built 4 files!"),
         exitCode: 0);
 
     d.dir(appPath, [
       d.dir('build', [
         d.nothing('file1.dart.js'),
-        d.nothing('file1.dart'),
+        d.matcherFile('file1.dart', isNot(isEmpty)),
         d.nothing('file2.dart.js'),
-        d.nothing('file2.dart'),
+        d.matcherFile('file2.dart', isNot(isEmpty)),
         d.nothing('file3.dart.js'),
-        d.nothing('file3.dart'),
+        d.matcherFile('file3.dart', isNot(isEmpty)),
         d.nothing('file4.dart.js'),
-        d.nothing('file4.dart')
+        d.matcherFile('file4.dart', isNot(isEmpty))
       ])
     ]).validate();
   });