Add test- and group-level support for skipping tests.

lib/src/runner/loader.dart

Index: lib/src/runner/loader.dart
diff --git a/lib/src/runner/loader.dart b/lib/src/runner/loader.dart
index 498b14bda176fe1b45019125ebf77b3707966af6..7652165d1eaaaf90c8ecc144f71ed6435928a7e1 100644
--- a/lib/src/runner/loader.dart
+++ b/lib/src/runner/loader.dart
@@ -11,6 +11,7 @@ import 'dart:isolate';
 import 'package:analyzer/analyzer.dart';
 import 'package:path/path.dart' as p;
 
+import '../backend/invoker.dart';
 import '../backend/metadata.dart';
 import '../backend/suite.dart';
 import '../backend/test_platform.dart';
@@ -129,6 +130,13 @@ class Loader {
         return new Future.value();
       }
 
+      // Don't load a skipped suite.
+      if (metadata.skip) {
+        return new Future.value(new Suite([
+          new LocalTest(path, metadata, () {})
+        ], path: path, platform: platform.name, metadata: metadata));
+      }
+
       return new Future.sync(() {
         if (_pubServeUrl != null && !p.isWithin('test', path)) {
           throw new LoadException(path,