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

tests/isolate/src/APIv2_spawnUriChildIsolate.dart

Index: tests/isolate/src/APIv2_spawnUriChildIsolate.dart
diff --git a/tests/isolate/src/APIv2_spawnUriChildIsolate.dart b/tests/isolate/src/APIv2_spawnUriChildIsolate.dart
index 3f91c319ffb71128bb82b975b8b6d0815906d9b7..8b355308dd121d8e03616ab20fe05c88340c76ae 100644
--- a/tests/isolate/src/APIv2_spawnUriChildIsolate.dart
+++ b/tests/isolate/src/APIv2_spawnUriChildIsolate.dart
@@ -6,14 +6,6 @@
 #library('SpawnUriChildIsolate');
 #import('dart:isolate');
 
-void isolateMain(ReceivePort port) {
-  port.receive((msg, reply) => reply.send("re: $msg"));
-}
-
-// Just for frog's sake.  TODO(eub): clean this up when we're able to.
-main() {
-  if (false) {
-    isolateMain(null);

[eub, 2012/02/29 00:20:14]

(What made this one go away?)

[Siggi Cherem (dart-lang), 2012/02/29 00:37:15]

Actually a combination of this CL and the introduction of 'dart:isolate':
- when I did the latter, we changed frog so that it generates isolate code if
this library is imported. This removed the adhoc trick of using "new
ReceivePort()" to indicate that we needed the isolate code in this program.

- after this CL, [main] is the child isolate's entrypoint, which unlike
[isolateMain], frog knows that it can't be tree-shaken.

-    new ReceivePort();
-  }
+void main() {
+  port.receive((msg, reply) => reply.send('re: $msg'));
 }