update the DOM API so that we implement using the property style access of properties which work natively in JS and avoid using getter/setter methods in the DOM library so that they can easily compile to JS too from the same org.w3c.dom API on the JVM

libraries/stdlib/test/dom/DomBuilderTest.kt

@@ -60,7 +60,7 @@ class DomBuilderTest() : TestCase() {
         assertEquals(1, doc["#id2"].size())
         assertEquals(1, doc["#id3"].size())
 
-        val root = doc.rootElement
+        val root = doc.documentElement
         if (root == null) {
             fail("No root!")
         } else {
@@ -120,7 +120,7 @@ class DomBuilderTest() : TestCase() {
         } else {
             fail("Not an Element $grandChild")
         }
-        val children = doc.rootElement.children()
+        val children = doc.documentElement.children()
         val xml = nodesToXmlString(children)
         println("root element has children: ${xml}")
         assertEquals(1, children.size())