Support dart2js in pub serve.

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

Index: sdk/lib/_internal/pub/test/transformer/dart2js/ignores_nonentrypoint_in_web_test.dart
diff --git a/sdk/lib/_internal/pub/test/serve/watch_modified_file_test.dart b/sdk/lib/_internal/pub/test/transformer/dart2js/ignores_nonentrypoint_in_web_test.dart
similarity index 53%
copy from sdk/lib/_internal/pub/test/serve/watch_modified_file_test.dart
copy to sdk/lib/_internal/pub/test/transformer/dart2js/ignores_nonentrypoint_in_web_test.dart
index 6cf610d3931dc93a811223b259603ed5ed0abe25..f5922e6ee25fd9fd35b89e1ba8a5d83ce5441773 100644
--- a/sdk/lib/_internal/pub/test/serve/watch_modified_file_test.dart
+++ b/sdk/lib/_internal/pub/test/transformer/dart2js/ignores_nonentrypoint_in_web_test.dart
@@ -4,31 +4,24 @@
 
 library pub_tests;
 
-import '../descriptor.dart' as d;
-import '../test_pub.dart';
-import 'utils.dart';
+import '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+import '../../serve/utils.dart';
 
 main() {
   initConfig();
-  integration("watches modifications to files", () {
+  integration("ignores a non-entrypoint library in web", () {
     d.dir(appPath, [
       d.appPubspec(),
       d.dir("web", [
-        d.file("index.html", "before")
+        d.file("notmain.dart", "foo() => print('hello');")
       ])
     ]).create();
 
     startPubServe();
-    requestShouldSucceed("index.html", "before");
-
-    d.dir(appPath, [
-      d.dir("web", [
-        d.file("index.html", "after")
-      ])
-    ]).create();
-
     waitForBuildSuccess();
-    requestShouldSucceed("index.html", "after");
+    requestShouldSucceed("notmain.dart", "foo() => print('hello');");
+    requestShould404("notmain.dart.js");
     endPubServe();
   });
 }