Always fail when trying to store to an undeclared global variable, even if it was found.

src/stub-cache.cc

Index: src/stub-cache.cc
diff --git a/src/stub-cache.cc b/src/stub-cache.cc
index 08954ba618ae7ef761a9e9a8df1fc8289fb9b9d9..0e8f755c9ff72612826d04f9be1aaf278bdefea5 100644
--- a/src/stub-cache.cc
+++ b/src/stub-cache.cc
@@ -1057,7 +1057,7 @@ static MaybeObject* ThrowReferenceError(String* name) {
   // can't use either LoadIC or KeyedLoadIC constructors.
   IC ic(IC::NO_EXTRA_FRAME, Isolate::Current());
   ASSERT(ic.target()->is_load_stub() || ic.target()->is_keyed_load_stub());
-  if (!ic.SlowIsContextual()) return HEAP->undefined_value();
+  if (!ic.SlowIsUndeclaredGlobal()) return HEAP->undefined_value();
 
   // Throw a reference error.
   HandleScope scope;