Use relative URIs for core library part-of statements.

sdk/lib/math/point.dart

 // 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 dart.math;
+
+part of "math.dart";
 
 /**
  * A utility class for representing two-dimensional positions.
  */
 class Point<T extends num> {
   final T x;
   final T y;
 
   const Point(T x, T y)
       : this.x = x,
@@ skipping 67 matching lines @@
    *
    * Squared distances can be used for comparisons when the actual value is not
    * required.
    */
   T squaredDistanceTo(Point<T> other) {
     var dx = x - other.x;
     var dy = y - other.y;
     return dx * dx + dy * dy;
   }
 }