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 
},
              });
            }
            _blurListener(event);
          });
          element.addEventListener("mousedown", event => {
            elementData.beforeInputValue = event.target.value;
            elementData.beforeInputSelectionRange = null;
          });
          element.addEventListener("keyup", event => {
            
            if (event.target.selectionStart === event.target.selectionEnd) {
              elementData.beforeInputSelectionRange = null;
            }
          });
          element.addEventListener("select", event => {
            elementData.beforeInputSelectionRange = [
              event.target.selectionStart,
              event.target.selectionEnd,
            ];
          });
          if ("Keystroke" in this.data.actions) {
            
            
            element.addEventListener("input", event => {
              let selStart = -1;
              let selEnd = -1;
              if (elementData.beforeInputSelectionRange) {
                [selStart, selEnd] = elementData.beforeInputSelectionRange;
              }