update some dijit infrastructure tests to AMD, stop using dojo/ready, prefer _WidgetBase to _Widget except when testing deprecated functionality, etc., refs #14279
add missing (indirect) dependency from dijit/Tree to dojo/query, needed since on.selector() used with a string for the selector, refs #16561 !strict
Fixes #16422.  Don't hide invalid option label in Select.
Fixes #16514.  Found that [].concat(val) is great for converting scalar or array values into arrays and works cross-frame.
since the parser will eventually only return a promise, start preparing for it now, refs #14591 !strict