isolates: remove Isolate2 interface, add top-level spawn functions, more comments

tests/isolate/src/APIv2_spawnBrowserNegativeTest.dart

Index: tests/isolate/src/APIv2_spawnBrowserNegativeTest.dart
diff --git a/tests/isolate/src/APIv2_spawnBrowserNegativeTest.dart b/tests/isolate/src/APIv2_spawnBrowserNegativeTest.dart
index dcf80a03bd882fd7c96b304bd99f8a2861f08e1b..9caab9db44787ffd1320fc22dbcba9f4a08682ed 100644
--- a/tests/isolate/src/APIv2_spawnBrowserNegativeTest.dart
+++ b/tests/isolate/src/APIv2_spawnBrowserNegativeTest.dart
@@ -4,24 +4,24 @@
 
 // Negative test to make sure that we are reaching all assertions.
 #library('spawn_tests');
-#import("../../../client/testing/unittest/unittest.dart");
-#import("dart:dom"); // import added so test.dart can treat this as a webtest.
-#import("dart:isolate");
+#import('../../../client/testing/unittest/unittest.dart');
+#import('dart:dom'); // import added so test.dart can treat this as a webtest.
+#import('dart:isolate');
 
-child(ReceivePort port) {
-  port.receive((msg, reply) => reply.send("re: $msg"));
+child() {
+  port.receive((msg, reply) => reply.send('re: $msg'));
 }
 
 main() {
-  asyncTest("message - reply chain", 1, () {
+  asyncTest('message - reply chain', 1, () {
     ReceivePort port = new ReceivePort();
     port.receive((msg, _) {
-      expect(msg).equals("re: hello"); // should be hi, not hello
+      expect(msg).equals('re: hello'); // should be hi, not hello
       port.close();
       callbackDone();
     });
 
-    Isolate2 c = new Isolate2.fromCode(child);
-    c.sendPort.send("hi", port.toSendPort());
+    SendPort s = spawnFunction(child);
+    s.send('hi', port.toSendPort());
   });
 }