Port two completion contributors for use by plugins

pkg/analyzer_plugin/test/utilities/completion/flutter_util.dart

Index: pkg/analyzer_plugin/test/utilities/completion/flutter_util.dart
diff --git a/pkg/analyzer_plugin/test/utilities/completion/flutter_util.dart b/pkg/analyzer_plugin/test/utilities/completion/flutter_util.dart
new file mode 100644
index 0000000000000000000000000000000000000000..9888006842125ad0abeca9fc7b7f7b13242ac98d
--- /dev/null
+++ b/pkg/analyzer_plugin/test/utilities/completion/flutter_util.dart
@@ -0,0 +1,24 @@
+// Copyright (c) 2017, 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.
+
+String flutterPkgLibPath = '/packages/flutter/lib';
+
+String get flutter_framework_code => '''
+class Widget {}
+class RenderObjectWidget extends Widget {}
+class StatelessWidget extends Widget {}
+abstract class StatefulWidget extends Widget { }
+class SingleChildRenderObjectWidget extends RenderObjectWidget {}
+class Transform extends SingleChildRenderObjectWidget {}
+class ClipRect extends SingleChildRenderObjectWidget { ClipRect.rect(){} }
+class AspectRatio extends SingleChildRenderObjectWidget {}
+class Container extends StatelessWidget { Container({child: null, width: null, height: null}){}}
+class Center extends StatelessWidget { Center({child: null, key: null}){}}
+class DefaultTextStyle extends StatelessWidget { DefaultTextStyle({child: null}){}}
+class Row extends Widget { Row({List<Widget> children: null, key: null}){}}
+class GestureDetector extends SingleChildRenderObjectWidget { GestureDetector({child: null, onTap: null}){}}
+class AppBar extends StatefulWidget implements PreferredSizeWidget { AppBar(title: null, color: null, key: null) }
+class Scaffold extends Widget { Scaffold({body: null, PreferredSizeWidget appBar: null}){}}
+class PreferredSizeWidget implements Widget {}
+''';