Add File.readAsBytesSync/writeAsBytesSync() methods.

pkg/analyzer/lib/file_system/file_system.dart

Index: pkg/analyzer/lib/file_system/file_system.dart
diff --git a/pkg/analyzer/lib/file_system/file_system.dart b/pkg/analyzer/lib/file_system/file_system.dart
index c9b3e96baf54391362ead2d3ed97ffc7bd84d2d2..093f47f04f84f62a8b96bc340ba75cadea3e0d71 100644
--- a/pkg/analyzer/lib/file_system/file_system.dart
+++ b/pkg/analyzer/lib/file_system/file_system.dart
@@ -32,10 +32,23 @@ abstract class File implements Resource {
   Source createSource([Uri uri]);
 
   /**
+   * Synchronously read the entire file contents as a list of bytes.
+   * Throws a [FileSystemException] if the operation fails.
+   */
+  List<int> readAsBytesSync();
+
+  /**
    * Synchronously read the entire file contents as a [String].
    * Throws [FileSystemException] if the file does not exist.
    */
   String readAsStringSync();
+
+  /**
+   * Synchronously write a list of bytes to the file.
+   *
+   * Throws a [FileSystemException] if the operation fails.
+   */
+  void writeAsBytesSync(List<int> bytes);
 }
 
 /**
@@ -63,7 +76,7 @@ abstract class Folder implements Resource {
 
   /**
    * If the path [path] is a relative path, convert it to an absolute path
-   * by interpreting it relative to this folder.  If it is already an aboslute
+   * by interpreting it relative to this folder.  If it is already an absolute
    * path, then don't change it.
    *
    * However, regardless of whether [path] is relative or absolute, normalize