Add PDBs to .isolate files so that tests show stack traces.

net/net_unittests.isolate

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 {
   'conditions': [
     ['OS=="android" or OS=="linux" or OS=="mac" or OS=="win"', {
       'variables': {
         'isolate_dependency_untracked': [
           'data/',
         ],
@@ skipping 14 matching lines @@
         'isolate_dependency_untracked': [
           '../third_party/pyftpdlib/',
           '../third_party/pywebsocket/',
           '../third_party/tlslite/',
           '<(PRODUCT_DIR)/pyproto/',
           'tools/testserver/',
         ],
         'read_only': 1,
       },
     }],
+    ['OS=="win"', {
+      'variables': {
+        'isolate_dependency_untracked': [
+          '<(PRODUCT_DIR)/net_unittests.exe.pdb',
+        ],
+      },
+    }],
   ],
   'includes': [
     '../base/base.isolate',
   ],
 }