Remove Flow workaround in buildASTSchema (#1697)

Author: IvanGoncharov

src/utilities/buildASTSchema.js

@@ -226,13 +226,10 @@ export class ASTDefinitionBuilder {
 
   getWrappedType(node: TypeNode): GraphQLType {
     if (node.kind === Kind.LIST_TYPE) {
-      return GraphQLList(this.getWrappedType(node.type));
+      return new GraphQLList(this.getWrappedType(node.type));
     }
     if (node.kind === Kind.NON_NULL_TYPE) {
-      return GraphQLNonNull(
-        // Note: GraphQLNonNull constructor validates this type
-        (this.getWrappedType(node.type): any),
-      );
+      return new GraphQLNonNull(this.getWrappedType(node.type));
     }
     return this.getNamedType(node);
   }