Fix remaining uses of Directory.systemTemp outside test scripts.

sdk/lib/core/object.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.
 
 part of dart.core;
 
 /**
  * The base class for all Dart objects.
  *
  * Because Object is the root of the Dart class hierarchy,
@@ skipping 60 matching lines @@
    * equality operator as well to maintain consistency.
    */
   external int get hashCode;
 
   /**
    * Returns a string representation of this object.
    */
   external String toString();
 
   /**
-   * [noSuchMethod] is invoked when users invoke a non-existant method
+   * [noSuchMethod] is invoked when users invoke a non-existent method
    * on an object. The name of the method and the arguments of the
    * invocation are passed to [noSuchMethod] in an [Invocation].
    * If [noSuchMethod] returns a value, that value becomes the result of
    * the original invocation.
    *
    * The default behavior of [noSuchMethod] is to throw a
    * [noSuchMethodError].
    */
   external dynamic noSuchMethod(Invocation invocation);
 
   /**
    * A representation of the runtime type of the object.
    */
   external Type get runtimeType;
 }