Web updates

HTML ab08b9bdea76

Standardize popup features and BarProp values Fixes #5872 by standardizing an internal "is popup" boolean, and how it is impacted by various features. Implementations can use this boolean (in addition to other signals) to determine whether an opened window is a popup or not. Fixes #4431 by changing the various BarProp visible properties to only reflect this "is popup" boolean, instead of reflecting the actual state of user interface elements, or the passed-in window features. Adds a "popup" feature to provide a simpler method of requesting a popup.