Extension method prefixed import tests.

Adds tests for the change to make extension members accessible even
for prefixed imports.  Also tests that it is an error to import a
library with extensions as deferred without hiding the extensions.

Change-Id: I3a81c560694d34c8adbb4cc86ca9e6b8a129ae56
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/124589
Commit-Queue: Leaf Petersen <leafp@google.com>
Reviewed-by: Bob Nystrom <rnystrom@google.com>

Author: leafpetersen

tests/language_2/extension_methods/helpers/also_on_object.dart

@@ -0,0 +1,8 @@
+// Copyright (c) 2019, 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.
+
+// An extension conflicting with the one from "on_object.dart";
+extension AlsoOnObject on Object {
+  String get onObject => "also object";
+}

tests/language_2/extension_methods/helpers/class_no_shadow.dart

@@ -2,8 +2,6 @@
 // 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.
 
-// SharedOptions=--enable-experiment=extension-methods
-
 import "package:expect/expect.dart";
 
 const String instanceValue = "1";

tests/language_2/extension_methods/helpers/class_shadow.dart

@@ -2,8 +2,6 @@
 // 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.
 
-// SharedOptions=--enable-experiment=extension-methods
-
 import "package:expect/expect.dart";
 
 import "class_no_shadow.dart";

tests/language_2/extension_methods/helpers/extension_all.dart

@@ -2,8 +2,6 @@
 // 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.
 
-// SharedOptions=--enable-experiment=extension-methods
-
 import "package:expect/expect.dart";
 import "class_no_shadow.dart";
 

tests/language_2/extension_methods/helpers/extension_global_instance.dart

@@ -2,8 +2,6 @@
 // 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.
 
-// SharedOptions=--enable-experiment=extension-methods
-
 import "package:expect/expect.dart";
 import "class_no_shadow.dart";
 

tests/language_2/extension_methods/helpers/extension_only.dart

@@ -2,8 +2,6 @@
 // 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.
 
-// SharedOptions=--enable-experiment=extension-methods
-
 import "package:expect/expect.dart";
 import "class_no_shadow.dart";
 

tests/language_2/extension_methods/helpers/global_scope.dart

@@ -2,8 +2,6 @@
 // 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.
 
-// SharedOptions=--enable-experiment=extension-methods
-
 import "package:expect/expect.dart";
 
 const int globalValue = 0;

tests/language_2/extension_methods/helpers/on_int.dart

@@ -0,0 +1,8 @@
+// Copyright (c) 2019, 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.
+
+extension OnInt on int {
+  String get onObject => "int";
+  String get onInt => "int";
+}

tests/language_2/extension_methods/helpers/on_object.dart

@@ -0,0 +1,7 @@
+// Copyright (c) 2019, 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.
+
+extension OnObject on Object {
+  String get onObject => "object";
+}

tests/language_2/extension_methods/static_extension_deferred_double_import_test.dart

@@ -0,0 +1,16 @@
+// Copyright (c) 2019, 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.
+
+import "package:expect/expect.dart";
+
+import "helpers/on_object.dart";
+import "helpers/on_object.dart" deferred as p1 hide OnObject;
+
+// Allow explicit and implicit access to non-deferred import extensions.
+
+void main() async {
+  Object o = 1;
+  Expect.equals("object", OnObject(o).onObject);
+  Expect.equals("object", o.onObject);
+}