message: fix(svg): use `offsetX/offsetY` instead of `layerX/layerY` when Firefox >= 39.
  To resolve the case where the chart uses SVG renderer and has shadow filter.
diff: @@ -67,6 +67,8 @@ export function clientToLocal(
  // <https://bugs.jquery.com/ticket/8523#comment:14>
  // BTW3, In ff, offsetX/offsetY is always 0.
  else if (env.browser.firefox
  + // use offsetX/offsetY for Firefox >= 39
  + // PENDING: consider Firefox for Android and Firefox OS? >= 43
  && env.browser.version < '39'
  && (e as FirefoxMouseEvent).layerX != null
  && (e as FirefoxMouseEvent).layerX !== (e as MouseEvent).offsetX
  @@ -74,7 +76,7 @@ export function clientToLocal(
  out.zrX = (e as FirefoxMouseEvent).layerX;
  out.zrY = (e as FirefoxMouseEvent).layerY;
  }
  - // For IE6+, chrome, safari, opera. (When will ff support offsetX?)
  + // For IE6+, chrome, safari, opera, firefox >= 39
  else if ((e as MouseEvent).offsetX != null) {
  out.zrX = (e as MouseEvent).offsetX;
  out.zrY = (e as MouseEvent).offsetY;
  