message: fix(svg): rebuild path when an element has no path.
  This can fix the shape may disappear after morphing animation is finished in SVG renderer.
diff: @@ -170,12 +170,13 @@ export function brushSVGPath(el: Path, scope: BrushScope) {
  builtinShpDef[0](shape, attrs, mul);
  }
  else {
  + const needBuildPath = !el.path || el.shapeChanged();
  if (!el.path) {
  el.createPathProxy();
  }
  const path = el.path;
  - if (el.shapeChanged()) {
  + if (needBuildPath) {
  path.beginPath();
  el.buildPath(path, el.shape);
  el.pathUpdated();
  