code: function propagateSyntax(parent) {
              if (parent['messages']) {
                  parent['messages'].forEach(function(child) {
                      child["syntax"] = parent["syntax"];
                      propagateSyntax(child);
                  });
              }
              if (parent['enums']) {
                  parent['enums'].forEach(function(child) {
                      child["syntax"] = parent["syntax"];
                  });
              }
          }
docs: Propagates syntax to all children.
  @param {!Object} parent
  @inner