fix Form.create types, close #2885

index.d.ts

@@ -552,7 +552,7 @@ export class FormItem extends React.Component<FormItemProps, {}> {
 }
 
 interface FormComponentProps {
-  form:CreateFormOptions
+  form?:CreateFormOptions
 }
 export class FormComponent extends React.Component<FormComponentProps, {}> {
 }