Revert hiding of VM-only coreimpl list implementation types. While I

runtime/bin/file_impl.dart

 // Copyright (c) 2012, 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.
 
 class _FileInputStream extends _BaseDataInputStream implements InputStream {
   _FileInputStream(String name)
       : _data = const [],
         _position = 0,
         _filePosition = 0 {
     var file = new File(name);
@@ skipping 317 matching lines @@
 
   static const SUCCESS_RESPONSE = 0;
   static const ILLEGAL_ARGUMENT_RESPONSE = 1;
   static const OSERROR_RESPONSE = 2;
   static const FILE_CLOSED_RESPONSE = 3;
 
   static const ERROR_RESPONSE_ERROR_TYPE = 0;
   static const OSERROR_RESPONSE_ERROR_CODE = 1;
   static const OSERROR_RESPONSE_MESSAGE = 2;
 
+  static List ensureFastAndSerializableBuffer(
+      List buffer, int offset, int bytes) {
+    // When using the Dart C API to access raw data, using a ByteArray is
+    // currently much faster. This function will make a copy of the
+    // supplied List to a ByteArray if it isn't already.
+    List outBuffer;
+    int outOffset = offset;
+    if (buffer is Uint8List || buffer is ObjectArray) {
+      outBuffer = buffer;
+    } else {
+      outBuffer = new Uint8List(bytes);
+      outOffset = 0;
+      int j = offset;
+      for (int i = 0; i < bytes; i++) {
+        int value = buffer[j];
+        if (value is! int) {
+          throw new FileIOException(
+              "List element is not an integer at index $j");
+        }
+        outBuffer[i] = value;
+        j++;
+      }
+    }
+    return [outBuffer, outOffset];
+  }
+
   static exists(String name) native "File_Exists";
   static open(String name, int mode) native "File_Open";
   static create(String name) native "File_Create";
   static delete(String name) native "File_Delete";
   static fullPath(String name) native "File_FullPath";
   static directory(String name) native "File_Directory";
   static lengthFromName(String name) native "File_LengthFromName";
   static lastModified(String name) native "File_LastModified";
   static int close(int id) native "File_Close";
   static readByte(int id) native "File_ReadByte";
   static readList(int id, List<int> buffer, int offset, int bytes)
       native "File_ReadList";
   static writeByte(int id, int value) native "File_WriteByte";
   static writeList(int id, List<int> buffer, int offset, int bytes) {
-    List result = _ensureFastAndSerializableBuffer(buffer, offset, bytes);
+    List result =
+        _FileUtils.ensureFastAndSerializableBuffer(buffer, offset, bytes);
     List outBuffer = result[0];
     int outOffset = result[1];
     return writeListNative(id, outBuffer, outOffset, bytes);
   }
   static writeListNative(int id, List<int> buffer, int offset, int bytes)
       native "File_WriteList";
   static writeString(int id, String string) native "File_WriteString";
   static position(int id) native "File_Position";
   static setPosition(int id, int position) native "File_SetPosition";
   static truncate(int id, int length) native "File_Truncate";
@@ skipping 549 matching lines @@
       new Timer(0, (t) {
           completer.completeException(new FileIOException(
           "Invalid arguments to writeList for file '$_name'"));
       });
       return completer.future;
     }
     if (closed) return _completeWithClosedException(completer);
 
     List result;
     try {
-      result = _ensureFastAndSerializableBuffer(buffer, offset, bytes);
+      result =
+          _FileUtils.ensureFastAndSerializableBuffer(buffer, offset, bytes);
     } catch (e) {
       // Complete asynchronously so the user has a chance to setup
       // handlers without getting exceptions when registering the
       // then handler.
       new Timer(0, (t) => completer.completeException(e));
       return completer.future;
     }
     List outBuffer = result[0];
     int outOffset = result[1];
 
@@ skipping 204 matching lines @@
           new FileIOException("File closed '$_name'"));
     });
     return completer.future;
   }
 
   final String _name;
   int _id;
 
   SendPort _fileService;
 }