Missing Javadoc comments on WebWindow.java lines 79-80

[ZaheerAhmadDev]

Ref : https://github.com/HtmlUnit/htmlunit/blob/master/src/main/java/org/htmlunit/WebWindow.java

WebWindow.java has two methods at lines 79-80 that are missing Javadoc comments.

This was caught by Checkstyle's MissingJavadocMethod check during CI.

See at : https://checkstyle.semaphoreci.com/jobs/a26d5f61-a96d-4bd1-88ab-9a3ab66ad985