message: Do not support "function" style until have to, because it might bring trouble in some cases like optimize, worker, ...
diff: @@ -5,8 +5,7 @@ import {
  each,
  normalizeCssArray,
  isString,
  - isObject,
  - isFunction
  + isObject
  } from '../../core/util';
  import * as textContain from '../../contain/text';
  import * as roundRectHelper from './roundRect';
  @@ -412,10 +411,6 @@ function drawBackground(hostEl, ctx, style, x, y, width, height) {
  ctx.fill();
  }
  }
  - else if (isFunction(textBackgroundColor)) {
  - setCtx(ctx, 'fillStyle', textBackgroundColor(style));
  - ctx.fill();
  - }
  else if (isObject(textBackgroundColor)) {
  var image = textBackgroundColor.image;
  