JSON Schema compiler: a tiny Python syntax fix

This works with more flavors / installs of Python without affecting
existing ones.

Change-Id: Ia3766d7e1c1359a25fd3b1ce91a740e658339480
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2443621
Auto-Submit: Manu Cornet <manucornet@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813168}

tools/json_schema_compiler/model.py

@@ -208,7 +208,7 @@ class Type(object):
     self.name = name
 
     # The typename "ManifestKeys" is reserved.
-    if name is 'ManifestKeys':
+    if name == 'ManifestKeys':
       assert parent == namespace and input_origin.from_manifest_keys, \
           'ManifestKeys type is reserved'