Add Object.hashCodeOf to get the default hashCode of an object.

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..c4c2ffb458343a66420f1f7b17154d4c8a3891cd 100644
--- a/sdk/lib/core/object.dart
+++ b/sdk/lib/core/object.dart
@@ -93,5 +93,14 @@ class Object {
    * A representation of the runtime type of the object.
    */
   external Type get runtimeType;
+
+  /**
+   * Returns the same value as [hashCode] on [object] would.
+   *
+   * If [object] hasn't overridden [hashCode] from [Object], this is the
+   * same as `object.hashCode`. This method can be used to get the object's
+   * hashCode event if `hashCode` has been overridden.
+   */
+  external static int hashCodeOf(Object object);

[kasperl, 2013/09/20 13:17:17]

How about calling this identityHashCode? Maybe consider moving it next to
identical() rather than sticking it in here?

 }