message: fix(svg): use self-defined `WeakMap` class instead of built-in object in browser.
diff: @@ -9,6 +9,7 @@ import Displayable from '../../graphic/Displayable';
  import {PatternObject} from '../../graphic/Pattern';
  import LRU from '../../core/LRU';
  import {createOrUpdateImage} from '../../graphic/helper/image';
  +import WeakMap from '../../core/WeakMap';
  function isPattern(value: PatternObject): value is PatternObject {
  return value && (!!value.image || !!value.svgElement);
  