Rework service extensions to be safe

runtime/lib/developer.cc

Index: runtime/lib/developer.cc
diff --git a/runtime/lib/developer.cc b/runtime/lib/developer.cc
index 464e89b2448327a2500cdde97b6e0a9e5c7ada8c..d2466af22cf8017fef9b6e59da37862b30521ed3 100644
--- a/runtime/lib/developer.cc
+++ b/runtime/lib/developer.cc
@@ -59,4 +59,18 @@ DEFINE_NATIVE_ENTRY(Developer_log, 8) {
   return Object::null();
 }
 
+
+DEFINE_NATIVE_ENTRY(Developer_lookupExtension, 1) {
+  GET_NON_NULL_NATIVE_ARGUMENT(String, name, arguments->NativeArgAt(0));
+  return isolate->LookupServiceExtensionHandler(name);
+}
+
+
+DEFINE_NATIVE_ENTRY(Developer_registerExtension, 2) {
+  GET_NON_NULL_NATIVE_ARGUMENT(String, name, arguments->NativeArgAt(0));
+  GET_NON_NULL_NATIVE_ARGUMENT(Instance, handler, arguments->NativeArgAt(1));
+  isolate->RegisterServiceExtensionHandler(name, handler);
+  return Object::null();
+}
+
 }  // namespace dart