PDF.js頁面寬度展示時去掉兩側留白

web/viewer.js的內容中：
有頁面寬度對應的放大值，只需要擴大1.05倍左右即可。

    var pageWidthScale = (this.container.clientWidth - hPadding) / currentPage.width * currentPage.scale;
    var pageHeightScale = (this.container.clientHeight - vPadding) / currentPage.height * currentPage.scale;

    switch (value) {
      case "page-actual":
        scale = 1;
        break;

      case "page-width":
        scale = pageWidthScale;
        break;

      case "page-height":
        scale = pageHeightScale;
        break;

      case "page-fit":
        scale = Math.min(pageWidthScale, pageHeightScale);
        break;

      case "auto":
        var horizontalScale = (0, _ui_utils.isPortraitOrientation)(currentPage) ? pageWidthScale : Math.min(pageHeightScale, pageWidthScale);
        scale = Math.min(_ui_utils.MAX_AUTO_SCALE, horizontalScale);
        scale = pageWidthScale * 1.0?;
        break;

      default:
        console.error("".concat(this._name, "._setScale: \"").concat(value, "\" is an unknown zoom value."));
        return;
    }