Update references to Mojo core and bindings

sky/examples/terminal/terminal_file_impl.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'dart:async';
 import 'dart:core';
-import 'dart:mojo.core';
+import 'package:mojo/public/dart/core.dart' as core;
 import 'package:mojo/services/files/public/interfaces/file.mojom.dart' as files;
 import 'package:mojo/services/files/public/interfaces/types.mojom.dart' as files;
 
 import 'terminal_display.dart';
 
 // This implements a |mojo.files.File| that acts like a (pseudo)terminal. Bytes
 // written to the |File| will be read by this implementation and passed on to
 // the (Dart) |TerminalDisplay| (using |putChar()|). A read from the |File| will
 // be completed if/when |TerminalDisplay| makes a byte available (via
 // |getChar()|).
@@ skipping 97 matching lines @@
     // TODO(vtl)
     return responseFactory(files.Error_UNIMPLEMENTED);
   }
 
   @override
   Future asBuffer(Function responseFactory) async {
     // TODO(vtl)
     return responseFactory(files.Error_UNIMPLEMENTED, null);
   }
 }