Create an app snapshot of the Dart front end.

utils/kernel-service/kernel-service.dart

Index: utils/kernel-service/kernel-service.dart
diff --git a/runtime/tools/kernel-service.dart b/utils/kernel-service/kernel-service.dart
similarity index 79%
rename from runtime/tools/kernel-service.dart
rename to utils/kernel-service/kernel-service.dart
index f473c154775f0376174f49614e7eb7ace589ec48..1351f97091ce1051bcce0b1901f8f4e92bd4f8d8 100644
--- a/runtime/tools/kernel-service.dart
+++ b/utils/kernel-service/kernel-service.dart
@@ -92,4 +92,26 @@ Future _processLoadRequest(request) async {
   port.send([tag, inputFileUrl, inputFileUrl, null, result]);
 }
 
-main() => new RawReceivePort()..handler = _processLoadRequest;
+// This entry point is used when running in the kernel isolate.
+start() => new RawReceivePort()..handler = _processLoadRequest;
+
+// This entry point is used when creating an app snapshot. The argument provides
+// a script to compile to warm-up generated code.
+main(args) {
+  var tag = 1;
+  var scriptUri = args[0];
+  var responsePort = new RawReceivePort();
+  responsePort.handler = (response) {
+    if (response[0] == tag) {
+      // Success.
+      responsePort.close();
+    } else if (response[0] == -tag) {
+      // Compilation error.
+      throw response[4];
+    } else {
+      throw "Unexpected response: $response";
+    }
+  };
+  var request = [tag, responsePort.sendPort, scriptUri];
+  _processLoadRequest(request);
+}