Remove legacy restart code

runtime/observatory/lib/src/service/object.dart

Index: runtime/observatory/lib/src/service/object.dart
diff --git a/runtime/observatory/lib/src/service/object.dart b/runtime/observatory/lib/src/service/object.dart
index c8cec35a83302425f354815ca2f2fbe5d85081c1..0978fd4857f305ca057b809cba5f514e27e6feef 100644
--- a/runtime/observatory/lib/src/service/object.dart
+++ b/runtime/observatory/lib/src/service/object.dart
@@ -853,10 +853,6 @@ abstract class VM extends ServiceObjectOwner implements M.VM {
     }
   }
 
-  Future restart() {
-    return invokeRpc('_restartVM', {});
-  }
-
   Future<Map> _fetchDirect({int count: kDefaultFieldLimit}) async {
     if (!loaded) {
       // The vm service relies on these events to keep the VM and