See JENKINS-70906. Jenkins core currently uses Prototype 1.7, released on November 15, 2010. The latest version is Prototype 1.7.3, released on September 22, 2015. When an attempt was made to upgrade to 1.7.3 in 2018 in JENKINS-49319, the change had to be reverted. Since this library has been unmaintained for the past 8 years, this PR removes any usages of it in favor of native JavaScript APIs.
See JENKINS-70906. Jenkins core currently uses Prototype 1.7, released on November 15, 2010. The latest version is Prototype 1.7.3, released on September 22, 2015. When an attempt was made to upgrade to 1.7.3 in 2018 in JENKINS-49319, the change had to be reverted. Since this library has been unmaintained for the past 8 years, this PR removes any usages of it in favor of native JavaScript APIs.