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 
errorFontLoadType3: "errorFontLoadType3",
  errorFontState: "errorFontState",
  errorFontMissing: "errorFontMissing",
  errorFontTranslate: "errorFontTranslate",
  errorColorSpace: "errorColorSpace",
  errorOperatorList: "errorOperatorList",
  errorFontToUnicode: "errorFontToUnicode",
  errorFontLoadNative: "errorFontLoadNative",
  errorFontGetPath: "errorFontGetPath",
  errorMarkedContent: "errorMarkedContent",
};
const PasswordResponses = {
  NEED_PASSWORD: 1,
  INCORRECT_PASSWORD: 2,
};
let verbosity = VerbosityLevel.WARNINGS;
function setVerbosityLevel(level) {
  if (Number.isInteger(level)) {
    verbosity = level;
  }
}
function getVerbosityLevel() {
  return verbosity;
}
function info(msg) {
  if (verbosity >= VerbosityLevel.INFOS) {
    console.log(`Info: ${msg}`);
  }
}
function warn(msg) {