Add writeString method to OutputStream

runtime/bin/file.dart

Index: runtime/bin/file.dart
diff --git a/runtime/bin/file.dart b/runtime/bin/file.dart
index 9728ab7cd92d338429781fb34974419b3fc74f25..03709352b2541f97719f573542643953caeecf3a 100644
--- a/runtime/bin/file.dart
+++ b/runtime/bin/file.dart
@@ -163,38 +163,37 @@ interface File default _File {
   List<int> readAsBytesSync();
 
   /**
-   * Read the entire file contents as text using the given [encoding]
-   * ('UTF-8', 'ISO-8859-1', 'ASCII').
+   * Read the entire file contents as text using the given
+   * [encoding]. The default encoding is UTF-8 - [:Encoding.UTF_8:].
    *
    * When the operation completes the callback is called. The
    * [onError] function registered on the file object is called if the
    * operation fails.
    */
-  void readAsText(String encoding, void callback(String text));
+  void readAsText(Encoding encoding, void callback(String text));
 
   /**
    * Synchronously read the entire file contents as text using the
-   * given [encoding] ('UTF-8', 'ISO-8859-1', 'ASCII'). By default the
-   * encoding is 'UTF-8'.
+   * given [encoding]. The default encoding is UTF-8 - [:Encoding.UTF_8:].
    */
-  String readAsTextSync([String encoding]);
+  String readAsTextSync([Encoding encoding]);
 
   /**
    * Read the entire file contents as lines of text using the give
-   * [encoding] ('UTF-8', 'ISO-8859-1', 'ASCII').
+   * [encoding]. The default encoding is UTF-8 - [:Encoding.UTF_8:].
    *
    * When the operation completes the callback is called. The
    * [onError] function registered on the file object is called if the
    * operation fails.
    */
-  void readAsLines(String encoding, void callback(List<String> lines));
+  void readAsLines(Encoding encoding, void callback(List<String> lines));
 
   /**
    * Synchronously read the entire file contents as lines of text
-   * using the given [encoding] ('UTF-8', 'ISO-8859-1', 'ASCII'). By
-   * default the encoding is 'UTF-8'.
+   * using the given [encoding] The default encoding is UTF-8 -
+   * [:Encoding.UTF_8:].
    */
-  List<String> readAsLinesSync([String encoding]);
+  List<String> readAsLinesSync([Encoding encoding]);
 
   /**
    * Get the name of the file.
@@ -276,19 +275,21 @@ interface RandomAccessFile {
   int writeListSync(List<int> buffer, int offset, int bytes);
 
   /**
-   * Write a string to the file. If the string cannot be written the
-   * [onError] is called. When all pending write operations have
-   * finished [onNoPendingWrites] is called.
+   * Write a string to the file using the given [encoding]. If the
+   * string cannot be written [onError] is called. The default
+   * encoding is UTF-8 - [:Encoding.UTF_8:].
+   *
+   * When all pending write operations have finished
+   * [onNoPendingWrites] is called.
    */
-  // TODO(ager): writeString should take an encoding.
-  void writeString(String string);
+  void writeString(String string, [Encoding encoding]);
 
   /**
-   * Synchronously write a single string to the file. Returns the number
-   * of characters successfully written.
+   * Synchronously write a single string to the file using the given
+   * [encoding]. Returns the number of characters successfully
+   * written. The default encoding is UTF-8 - [:Encoding.UTF_8:].
    */
-  // TODO(ager): writeStringSync should take an encoding.
-  int writeStringSync(String string);
+  int writeStringSync(String string, [Encoding encoding]);
 
   /**
    * Get the current byte position in the file. When the operation