Do not return this on RandomAccessFile.close

Bug: 32015
Change-Id: I98508bdad569201afeed91f1287f061b5bb39a31
Reviewed-on: https://dart-review.googlesource.com/44060
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Commit-Queue: Vyacheslav Egorov <vegorov@google.com>

Author: lexaknyazev

sdk/lib/io/file.dart

@@ -609,10 +609,10 @@ abstract class File implements FileSystemEntity {
  */
 abstract class RandomAccessFile {
   /**
-   * Closes the file. Returns a `Future<RandomAccessFile>` that
+   * Closes the file. Returns a `Future` that
    * completes with this RandomAccessFile when it has been closed.
    */
-  Future<RandomAccessFile> close();
+  Future<void> close();
 
   /**
    * Synchronously closes the file.

sdk/lib/io/file_impl.dart

@@ -685,15 +685,13 @@ class _RandomAccessFile implements RandomAccessFile {
     }
   }
 
-  Future<RandomAccessFile> close() {
+  Future<void> close() {
     return _dispatch(_FILE_CLOSE, [null], markClosed: true).then((result) {
-      if (result != -1) {
-        closed = closed || (result == 0);
-        _maybePerformCleanup();
-        return this;
-      } else {
+      if (result == -1) {
         throw new FileSystemException("Cannot close file", path);
       }
+      closed = closed || (result == 0);
+      _maybePerformCleanup();
     });
   }
 

tests/compiler/dart2js/old_frontend/analyze_api_test.dart

@@ -18,7 +18,14 @@ import 'package:async_helper/async_helper.dart';
  * the error/warning message in the list of white-listings for each file.
  */
 // TODO(johnniwinther): Support canonical URIs as keys.
-const Map<String, List<String>> WHITE_LIST = const {};
+const Map<String, List<String>> WHITE_LIST = const {
+  "sdk/lib/io/file.dart": const [
+    "'void' is not a subtype of bound 'Object' for type variable",
+  ],
+  "sdk/lib/io/file_impl.dart": const [
+    "'void' is not a subtype of bound 'Object' for type variable",
+  ],
+};
 
 void main() {
   var uriList = new List<Uri>();

tests/compiler/dart2js/old_frontend/analyze_unused_dart2js_test.dart

@@ -62,6 +62,14 @@ const Map<String, List<String>> WHITE_LIST = const {
   "pkg/compiler/lib/src/js_backend/runtime_types.dart": const [
     "'void' is not a subtype of bound 'Object' for type variable",
   ],
+
+  "sdk/lib/io/file.dart": const [
+    "'void' is not a subtype of bound 'Object' for type variable",
+  ],
+
+  "sdk/lib/io/file_impl.dart": const [
+    "'void' is not a subtype of bound 'Object' for type variable",
+  ],
 };
 
 void main() {