cleanup patch generation to preseve comments and remove @patch

test/generated_sdk/lib/async/deferred_load.dart

Index: test/generated_sdk/lib/async/deferred_load.dart
diff --git a/test/generated_sdk/lib/async/deferred_load.dart b/test/generated_sdk/lib/async/deferred_load.dart
index 60f4f3ab2a10cd347a45d0c74ef3ccf5032f8f84..01b2c16e161e64055122f072c16bba55779d7136 100644
--- a/test/generated_sdk/lib/async/deferred_load.dart
+++ b/test/generated_sdk/lib/async/deferred_load.dart
@@ -17,7 +17,12 @@ class DeferredLibrary {
 
   const DeferredLibrary(this.libraryName, {this.uri});
 
-  @patch
+  /**
+   * Ensure that [libraryName] has been loaded.
+   *
+   * If the library fails to load, the Future will complete with a
+   * DeferredLoadException.
+   */
   Future<Null> load() {
     throw 'DeferredLibrary not supported. '
           'please use the `import "lib.dart" deferred as lib` syntax.';