jsdom, js: start refactoring jsdom; improve JS interfaces; add two attributes for them (#12488)

examples/js_dom_draw/draw.js.v

@@ -1,3 +1,4 @@
+/*
 import jsdom
 
 fn get_2dcontext(canvas jsdom.IElement) ?jsdom.CanvasRenderingContext2D {
@@ -74,3 +75,8 @@ fn main() {
 		context.clear_rect(0, 0, canv.width(), canv.height())
 	})
 }
+*/
+
+fn main() {
+	panic('jsdom is being refactored; This example will be available soon')
+}