Don't include source maps in release mode.

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

Index: sdk/lib/_internal/pub/test/transformer/dart2js/omits_source_map_in_release_test.dart
diff --git a/sdk/lib/_internal/pub/test/transformer/dart2js/converts_entrypoint_in_web_test.dart b/sdk/lib/_internal/pub/test/transformer/dart2js/omits_source_map_in_release_test.dart
similarity index 60%
copy from sdk/lib/_internal/pub/test/transformer/dart2js/converts_entrypoint_in_web_test.dart
copy to sdk/lib/_internal/pub/test/transformer/dart2js/omits_source_map_in_release_test.dart
index 90ad051152442fcfc8c1634457b5c1b4e56425f1..e4548d6fdb7320e9924dd986abae9f81b27ecbf6 100644
--- a/sdk/lib/_internal/pub/test/transformer/dart2js/converts_entrypoint_in_web_test.dart
+++ b/sdk/lib/_internal/pub/test/transformer/dart2js/omits_source_map_in_release_test.dart
@@ -4,15 +4,12 @@
 
 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("converts a Dart entrypoint in web to JS", () {
+  integration("omits source maps from a release build", () {
     d.dir(appPath, [
       d.appPubspec(),
       d.dir("web", [
@@ -20,8 +17,16 @@ main() {
       ])
     ]).create();
 
-    pubServe();
-    requestShouldSucceed("main.dart.js", contains("hello"));
-    endPubServe();
+    schedulePub(args: ["build"],
+        output: new RegExp(r'Built 2 files to "build".'),
+        exitCode: 0);
+
+    d.dir(appPath, [
+      d.dir('build', [
+        d.dir('web', [
+          d.nothing('main.dart.js.map')
+        ])
+      ])
+    ]).validate();
   });
 }