Table: allow filterable without filter-method

Author: jikkai

packages/table/src/table-column.js

@@ -270,7 +270,7 @@ export default {
       fixed: this.fixed === '' ? true : this.fixed,
       filterMethod: this.filterMethod,
       filters: this.filters,
-      filterable: this.filters && this.filters.length && this.filterMethod,
+      filterable: (this.filters && this.filters.length) || this.filterMethod,
       filterMultiple: this.filterMultiple,
       filterOpened: false,
       filteredValue: this.filteredValue || [],