Fix store IC writability check in strict mode.

src/ic.cc

Index: src/ic.cc
diff --git a/src/ic.cc b/src/ic.cc
index 78694dcb5628c5adfe8de1d839cb00febcdba3cb..b8d4b40bc918843b28a438f4f67e21209cee6709 100644
--- a/src/ic.cc
+++ b/src/ic.cc
@@ -1360,7 +1360,7 @@ MaybeObject* StoreIC::Store(State state,
       // Strict mode doesn't allow setting non-existent global property
       // or an assignment to a read only property.
       if (strict_mode == kStrictMode) {
-        if (lookup.IsFound() && lookup.IsReadOnly()) {
+        if (lookup.IsProperty() && lookup.IsReadOnly()) {
           return TypeError("strict_read_only_property", object, name);
         } else if (IsContextual(object)) {
           return ReferenceError("not_defined", name);