Fix trailing space from #1400 (#1409)

Author: IvanGoncharov

src/graphql.js

@@ -37,7 +37,7 @@ import type { MaybePromise } from './jsutils/MaybePromise';
  *    The value provided as the first argument to resolver functions on the top
  *    level type (e.g. the query object type).
  * contextValue:
- *    The context value is provided as an argument to resolver functions after 
+ *    The context value is provided as an argument to resolver functions after
  *    field arguments. It is used to pass shared information useful at any point
  *    during executing this query, for example the currently logged in user and
  *    connections to databases or other services.