Use Object::null_instance and Object::null_function and do not create Handles everytime.

runtime/vm/bootstrap.cc

Index: runtime/vm/bootstrap.cc
diff --git a/runtime/vm/bootstrap.cc b/runtime/vm/bootstrap.cc
index b844d0143fe8eabe712eb45536fb00ade464df10..a9b94853c9fb58dccdf4b9b0228dd585c4d3c084 100644
--- a/runtime/vm/bootstrap.cc
+++ b/runtime/vm/bootstrap.cc
@@ -154,7 +154,7 @@ static RawError* Compile(const Library& library, const Script& script) {
     } else {
       // Compilation errors are not Dart instances, so just mark the library
       // as having failed to load without providing an error instance.
-      library.SetLoadError(Instance::Handle());
+      library.SetLoadError(Object::null_instance());
     }
   }
   return error.raw();