[serializer] small fixes for blink snapshot.

PRESUBMIT.py

Index: PRESUBMIT.py
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 78e7482efbab5da80a2a0f5b8efa40ca4861c79d..ad218330b180a4c0ee1a379dfa4e8c2ccda98421 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -67,7 +67,6 @@ def _V8PresubmitChecks(input_api, output_api):
         input_api.PresubmitLocalPath(), 'tools'))
   from presubmit import CppLintProcessor
   from presubmit import SourceProcessor
-  from presubmit import CheckExternalReferenceRegistration
   from presubmit import CheckAuthorizedAuthor
   from presubmit import CheckStatusFiles
 
@@ -78,9 +77,6 @@ def _V8PresubmitChecks(input_api, output_api):
     results.append(output_api.PresubmitError(
         "Copyright header, trailing whitespaces and two empty lines " \
         "between declarations check failed"))
-  if not CheckExternalReferenceRegistration(input_api.PresubmitLocalPath()):
-    results.append(output_api.PresubmitError(
-        "External references registration check failed"))
   if not CheckStatusFiles(input_api.PresubmitLocalPath()):
     results.append(output_api.PresubmitError("Status file check failed"))
   results.extend(CheckAuthorizedAuthor(input_api, output_api))