code: function StaticAsset(element) {
    var supported = false;
    for (var type in propertyMap) {
      if (global[type] && element instanceof global[type]) {
        supported = true;
        this._widthProp = propertyMap[type][0];
        this._heightProp = propertyMap[type][1];
        break;
      }
    }
    if (!supported) {
      throw new Error('Unsupported pixel source');
    }
  
    this._element = element;
  }
docs: @class StaticAsset
  @implements Asset
  @classdesc
  
  An immutable {@link Asset} compatible with {@link WebGlStage} and
  {@link CssStage}.
  
  @param {HTMLImageElement|HTMLCanvasElement|ImageBitmap} element The
  underlying pixel source.
  @throws If the pixel source is unsupported.