Revert "Use relative URIs for core library part-of statements."

sdk/lib/math/jenkins_smi_hash.dart

Index: sdk/lib/math/jenkins_smi_hash.dart
diff --git a/sdk/lib/math/jenkins_smi_hash.dart b/sdk/lib/math/jenkins_smi_hash.dart
index d6aaac1089c34065e282804701bd13343bd17e4c..1fc7ddaddcff3e3302881a7f878846126539d1c2 100644
--- a/sdk/lib/math/jenkins_smi_hash.dart
+++ b/sdk/lib/math/jenkins_smi_hash.dart
@@ -1,8 +1,7 @@
 // Copyright (c) 2013, 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 "math.dart";
+part of dart.math;
 
 /**
  * This is the [Jenkins hash function][1] but using masking to keep