unittest step2: bye bye to multiple entrypoints for unittest

client/tests/client/dom/DOMIsolatesTest.dart

 #library('DOMIsolatesTest');
-#import('../../../../lib/unittest/unittest_dom.dart');
+#import('../../../../lib/unittest/unittest.dart');
+#import('../../../../lib/unittest/dom_config.dart');
 #import('dart:dom');
 #import('dart:isolate');
 
 isolateMain(port) {
   port.receive((msg, replyTo) {
     if (msg != 'check') {
       replyTo.send('wrong msg: $msg');
     }
     replyTo.send(window.location.toString());
     port.close();
   });
 }
 
 isolateMainTrampoline(port) {
   final childPortFuture = spawnDomIsolate(window, 'isolateMain');
   port.receive((msg, parentPort) {
     childPortFuture.then((childPort) {
       childPort.call(msg).then((response) {
         parentPort.send(response);
         port.close();
       });
     });
   });
 }
 
 main() {
-  forLayoutTests();
+  useDomConfiguration();
 
   final iframe = document.createElement('iframe');
   document.body.appendChild(iframe);
 
   asyncTest('Simple DOM isolate test', 1, () {
     spawnDomIsolate(iframe.contentWindow, 'isolateMain').then((sendPort) {
       sendPort.call('check').then((msg) {
         Expect.equals('about:blank', msg);
         callbackDone();
       });
@@ skipping 10 matching lines @@
   });
 
   test('Null as target window', () {
     expectThrow(() => spawnDomIsolate(null, 'isolateMain'));
   });
 
   test('Not window as target window', () {
     expectThrow(() => spawnDomIsolate(document, 'isolateMain'));
   });
 }