Clean Dom and Dom tests.

libraries/stdlib/src/kotlin/dom/Dom.kt

@@ -333,13 +333,7 @@ public fun NodeList?.toXmlString(xmlDeclaration: Boolean = false): String {
 
 /** Converts the collection of nodes to an XML String */
 public fun nodesToXmlString(nodes: Iterable<Node>, xmlDeclaration: Boolean = false): String {
-    // TODO this should work...
-    // return this.map{it.toXmlString()}.join("")
-    val builder = StringBuilder()
-    for (n in nodes) {
-        builder.append(n.toXmlString(xmlDeclaration))
-    }
-    return builder.toString()
+    return nodes.map { it.toXmlString(xmlDeclaration) }.join()
 }
 
 // Syntax sugar

libraries/stdlib/src/kotlin/dom/DomEvents.kt

@@ -5,23 +5,17 @@ import org.w3c.dom.Node
 import org.w3c.dom.events.*
 
 /**
-* Turns an event handler function into an [EventListener]
-*/
+ * Turns an event handler function into an [EventListener]
+ */
 public fun eventHandler(handler: (Event) -> Unit): EventListener {
     return EventListenerHandler(handler)
 }
 
 private class EventListenerHandler(private val handler: (Event) -> Unit) : EventListener {
     public override fun handleEvent(e: Event) {
-        if (e != null) {
-            handler(e)
-        }
+        handler(e)
     }
-/*
-    TODO: needs KT-2507 fixed
-
-    public override fun toString(): String? = "EventListenerHandler($handler)"
-*/
+    public override fun toString(): String = "EventListenerHandler($handler)"
 }
 
 public fun mouseEventHandler(handler: (MouseEvent) -> Unit): EventListener {
@@ -56,16 +50,12 @@ private class CloseableEventListener(
         private val listener: EventListener,
         private val name: String,
         private val capture: Boolean
-) : Closeable {
+                                    ) : Closeable {
     public override fun close() {
         target.removeEventListener(name, listener, capture)
     }
 
-/*
-    TODO: needs KT-2507 fixed
-
-    public override fun toString(): String? = "CloseableEventListener($target, $name)"
-*/
+    public override fun toString(): String = "CloseableEventListener($target, $name)"
 }
 
 public fun Node?.onClick(capture: Boolean = false, handler: (MouseEvent) -> Unit): Closeable? {

libraries/stdlib/src/kotlin/dom/DomJVM.kt

@@ -156,12 +156,12 @@ public fun Element.removeClass(cssClass: String): Boolean {
 
 /** Creates a new document with the given document builder*/
 public fun createDocument(builder: DocumentBuilder): Document {
-    return builder.newDocument()!!
+    return builder.newDocument()
 }
 
 /** Creates a new document with an optional DocumentBuilderFactory */
 public fun createDocument(builderFactory: DocumentBuilderFactory = defaultDocumentBuilderFactory()): Document {
-    return createDocument(builderFactory.newDocumentBuilder()!!)
+    return createDocument(builderFactory.newDocumentBuilder())
 }
 
 /**
@@ -175,7 +175,7 @@ public fun defaultDocumentBuilderFactory(): DocumentBuilderFactory {
  * Returns the default [[DocumentBuilder]]
  */
 public fun defaultDocumentBuilder(builderFactory: DocumentBuilderFactory = defaultDocumentBuilderFactory()): DocumentBuilder {
-    return builderFactory.newDocumentBuilder()!!
+    return builderFactory.newDocumentBuilder()
 }
 
 /**