Add an option to run skipped tests.

test/runner/configuration/top_level_test.dart

Index: test/runner/configuration/top_level_test.dart
diff --git a/test/runner/configuration/top_level_test.dart b/test/runner/configuration/top_level_test.dart
index 3f1f571762dca7b4d9df3192e0fe3f953ae2a157..2ebab89a9ded89346f4317b8722bf7c2983a603c 100644
--- a/test/runner/configuration/top_level_test.dart
+++ b/test/runner/configuration/top_level_test.dart
@@ -79,6 +79,25 @@ void main() {
     test.shouldExit(0);
   }, tags: 'content-shell');
 
+  test("runs skipped tests with run_skipped: true", () {
+    d.file("dart_test.yaml", JSON.encode({
+      "run_skipped": true
+    })).create();
+
+    d.file("test.dart", """
+      import 'package:test/test.dart';
+
+      void main() {
+        test("skip", () => print("In test!"), skip: true);
+      }
+    """).create();
+
+    var test = runTest(["test.dart"]);
+    test.stdout.expect(consumeThrough(contains("In test!")));
+    test.stdout.expect(consumeThrough(contains("+1: All tests passed!")));
+    test.shouldExit(0);
+  });
+
   test("includes the full stack with verbose_trace: true", () {
     d.file("dart_test.yaml", JSON.encode({
       "verbose_trace": true