Remove mirrors in product mode

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 71cf46c80aa6abf0e4c7f05e21e3daf16ff94b0a..93f2818be2c00f6f948d0d9afdcc0d3d6ec9ae39 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -1365,6 +1365,7 @@ RawError* Object::Init(Isolate* isolate) {
 
   // Pre-register the mirrors library so we can place the vm class
   // MirrorReference there rather than the core library.
+NOT_IN_PRODUCT(
   lib = Library::LookupLibrary(Symbols::DartMirrors());
   if (lib.IsNull()) {
     lib = Library::NewLibraryHelper(Symbols::DartMirrors(), true);
@@ -1376,7 +1377,7 @@ RawError* Object::Init(Isolate* isolate) {
   ASSERT(lib.raw() == Library::MirrorsLibrary());
 
   cls = Class::New<MirrorReference>();
-  RegisterPrivateClass(cls, Symbols::_MirrorReference(), lib);
+  RegisterPrivateClass(cls, Symbols::_MirrorReference(), lib));
 
   // Pre-register the collection library so we can place the vm class
   // LinkedHashMap there rather than the core library.