Mojo: Mojom: Remove redundant line.

Per review comment from https://codereview.chromium.org/398553002/. Note
that I'm keeping the |pass| and deleting the redundant assignment (so
now the |pass| is required). The alternative would be to nest the other
|if|s inside an |if ... is not None|, but I find that harder to read.

TBR=davemoore@chromium.org

Review URL: https://codereview.chromium.org/396243006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@283605 0039d316-1c4b-4281-b951-d872f2087c98

mojo/public/tools/bindings/pylib/mojom/parse/ast.py

@@ -36,7 +36,6 @@ class NodeListBase(NodeBase):
     self.items = []
     if item_or_items is None:
       pass
-      self.items = []
     elif isinstance(item_or_items, list):
       for item in item_or_items:
         assert isinstance(item, self._list_item_type)