lib32/ doesn't exist on OSX x64 build. Update browser_tests accordingly.

tools/isolate_driver.py

 #!/usr/bin/env python
 # 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.
 
 """Adaptor script called through build/isolate.gypi.
 
 Creates a wrapping .isolate which 'includes' the original one, that can be
 consumed by tools/swarming_client/isolate.py. Path variables are determined
 based on the current working directory. The relative_cwd in the .isolated file
@@ skipping 162 matching lines @@
       return i[:-4]
     if i.endswith('.dll.lib'):
       # Remove only the suffix .lib, not the .dll!
       return i[:-4]
     return i
 
   def f(i):
     # This script is only for adding new binaries that are created as part of
     # the component build.
     ext = os.path.splitext(i)[1]
-    if ext not in ['.dll', '.so', '.dylib']:
+    if ext not in ['.dll', '.nexe', '.so', '.dylib']:
       return False
 
     # Check for execute access and strip directories. This gets rid of all the
     # phony rules.
     p = os.path.join(build_dir, i)
     return os.access(p, os.X_OK) and not os.path.isdir(p)
 
   return filter(f, map(filter_item, dependencies))
 
 
@@ skipping 105 matching lines @@
 
   swarming_client = os.path.join(SRC_DIR, 'tools', 'swarming_client')
   sys.stdout.flush()
   result = subprocess.call(
       [sys.executable, os.path.join(swarming_client, 'isolate.py')] + args)
   return result
 
 
 if __name__ == '__main__':
   sys.exit(main())