convert Editor_mouse.html to AMD, and stop using internal editor command for selecting all the text, refs #14279
Move this.open() call from postCreate() to startup().   Fixes problem with double call to iframe's onload method when !StackContainer._setupChild() messes around with the DOM.   Also probably allows Editor creation without specifying a srcNodeRef.   It does require calling Editor.startup() though.   Refs #16244 ([29904]), fixes #16756 !strict.