In the following spots a "MouseUp" eventName is being used, which does look inconsistent considering that the "Mouse Down"/"Mouse Enter"/"Mouse Exit" eventNames all have a space in them.
Is this inconsistency actually expected, or is it a simple typo? If the former, then a comment explaining *why* would be appropriate; otherwise we should just fix this :-)

 - https://github.com/mozilla/pdf.js/blob/25b84ce84c95ba06d1ee57e578672048269c39c1/src/display/annotation_layer.js#L806

 - https://github.com/mozilla/pdf.js/blob/25b84ce84c95ba06d1ee57e578672048269c39c1/src/display/annotation_layer.js#L945

 - https://github.com/mozilla/pdf.js/blob/25b84ce84c95ba06d1ee57e578672048269c39c1/src/display/annotation_layer.js#L1034

 - https://github.com/mozilla/pdf.js/blob/25b84ce84c95ba06d1ee57e578672048269c39c1/src/display/annotation_layer.js#L1168

/cc @calixteman 
} else if (id === "page") {
        this._document.obj._dispatchPageEvent(
          event.name,
          baseEvent.actions,
          baseEvent.pageNumber
        );
      }
      return;
    }
    const name = baseEvent.name.replace(" ", "");
    const source = this._objects[id];
    const event = (globalThis.event = new Event(baseEvent));
    let savedChange;
    if (source.obj._isButton()) {
      source.obj._id = id;
      event.value = source.obj._getExportValue(event.value);
      if (name === "Action") {
        source.obj._value = event.value;
      }
    }
    if (name === "Keystroke") {
      savedChange = {
        value: event.value,
        change: event.change,
        selStart: event.selStart,
        selEnd: event.selEnd,
      };
    } else if (name === "Blur" || name === "Focus") {
      Object.defineProperty(event, "value", {
        configurable: false,