Make it possible to share the embedder's dart sources for the vmservice

runtime/lib/vmservice.cc

Index: runtime/lib/vmservice.cc
diff --git a/runtime/lib/vmservice.cc b/runtime/lib/vmservice.cc
index 83a25e1b98e05a308b81b42abe60bf470afee8a2..81a49c061f5990412988fd1e778a66a6e4402a6d 100644
--- a/runtime/lib/vmservice.cc
+++ b/runtime/lib/vmservice.cc
@@ -134,6 +134,17 @@ DEFINE_NATIVE_ENTRY(VMService_OnExit, 0) {
 }
 
 
+DEFINE_NATIVE_ENTRY(VMService_OnServerAddressChange, 1) {
+  GET_NATIVE_ARGUMENT(String, address, arguments->NativeArgAt(0));
+  if (address.IsNull()) {
+    ServiceIsolate::SetServerAddress(NULL);
+  } else {
+    ServiceIsolate::SetServerAddress(address.ToCString());
+  }
+  return Object::null();
+}
+
+
 DEFINE_NATIVE_ENTRY(VMService_ListenStream, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(String, stream_id, arguments->NativeArgAt(0));
   bool result = Service::ListenStream(stream_id.ToCString());