[tracing] Move math utilities from base into their own subdirectory (attempt 2)

tracing/tracing/base/math/rect.html

Index: tracing/tracing/base/math/rect.html
diff --git a/tracing/tracing/base/rect.html b/tracing/tracing/base/math/rect.html
similarity index 97%
rename from tracing/tracing/base/rect.html
rename to tracing/tracing/base/math/rect.html
index 1ceb39933bcdffb7a2776a3276a60e2132ec9541..a89d9b9262e650e984f415f8fec524bdbbbe8164 100644
--- a/tracing/tracing/base/rect.html
+++ b/tracing/tracing/base/math/rect.html
@@ -5,11 +5,11 @@ Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 -->
 <link rel="import" href="/tracing/base/base.html">
-<link rel="import" href="/tracing/base/math.html">
+<link rel="import" href="/tracing/base/math/math.html">
 <script>
 'use strict';
 
-tr.exportTo('tr.b', function() {
+tr.exportTo('tr.b.math', function() {
   /**
    * Tracks a 2D bounding box.
    * @constructor