Clean up tests that are duplicated between install and update.

sdk/lib/_internal/pub/test/hosted/fail_gracefully_on_url_resolve_test.dart

+// Copyright (c) 2012, 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 pub_tests;
+
+import 'dart:io';
+
+import '../descriptor.dart' as d;
+import '../test_pub.dart';
+
+main() {
+  initConfig();
+
+  forBothPubInstallAndUpdate((command) {
+    integration('fails gracefully if the url does not resolve', () {
+      d.dir(appPath, [
+        d.pubspec({
+          "name": "myapp",
+          "dependencies": {
+            "foo": {
+              "hosted": {
+                "name": "foo",
+                "url": "http://pub.invalid"
+              }
+            }
+           }
+        })
+      ]).create();
+
+      pubCommand(command, error:
+        new RegExp('Could not resolve URL "http://pub.invalid".'));
+    });
+  });
+}