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 
if (!ignoreBorder && data.borderStyle.width > 0) {
      container.style.borderWidth = `${data.borderStyle.width}px`;
      if (data.borderStyle.style !== AnnotationBorderStyleType.UNDERLINE) {
        
        
        
        width = width - 2 * data.borderStyle.width;
        height = height - 2 * data.borderStyle.width;
      }
      const horizontalRadius = data.borderStyle.horizontalCornerRadius;
      const verticalRadius = data.borderStyle.verticalCornerRadius;
      if (horizontalRadius > 0 || verticalRadius > 0) {
        const radius = `${horizontalRadius}px / ${verticalRadius}px`;
        container.style.borderRadius = radius;
      }
      switch (data.borderStyle.style) {
        case AnnotationBorderStyleType.SOLID:
          container.style.borderStyle = "solid";
          break;
        case AnnotationBorderStyleType.DASHED:
          container.style.borderStyle = "dashed";
          break;
        case AnnotationBorderStyleType.BEVELED:
          warn("Unimplemented border style: beveled");
          break;
        case AnnotationBorderStyleType.INSET:
          warn("Unimplemented border style: inset");
          break;
        case AnnotationBorderStyleType.UNDERLINE:
          container.style.borderBottomStyle = "solid";