Fix remaining uses of Directory.systemTemp outside test scripts.

sdk/lib/core/object.dart

Index: sdk/lib/core/object.dart
diff --git a/sdk/lib/core/object.dart b/sdk/lib/core/object.dart
index 975a8a79b4bfd34c770f99c633d6ccb75e4fb1a0..7879e7ac53fe1e286bc685b78508d798086a6784 100644
--- a/sdk/lib/core/object.dart
+++ b/sdk/lib/core/object.dart
@@ -78,7 +78,7 @@ class 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