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

tools/isolate_driver.py

Index: tools/isolate_driver.py
diff --git a/tools/isolate_driver.py b/tools/isolate_driver.py
index e5c5a3073a46164c6388ff653fad7d8547c357ef..23dceadeb1cd255186e5a16ec20717e1a3c1a20d 100755
--- a/tools/isolate_driver.py
+++ b/tools/isolate_driver.py
@@ -180,7 +180,7 @@ def post_process_deps(build_dir, dependencies):
     # 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