[strong] Implement strong mode restrictions on property access

src/ic/ic-inl.h

Index: src/ic/ic-inl.h
diff --git a/src/ic/ic-inl.h b/src/ic/ic-inl.h
index 55572f75277ea20f28537596cda393ed6a183709..7758fa39039dd8de18fd8397ab1d8c36fcb45989 100644
--- a/src/ic/ic-inl.h
+++ b/src/ic/ic-inl.h
@@ -135,6 +135,9 @@ void LoadIC::set_target(Code* code) {
   // The contextual mode must be preserved across IC patching.
   DCHECK(LoadICState::GetContextualMode(code->extra_ic_state()) ==
          LoadICState::GetContextualMode(target()->extra_ic_state()));
+  // Strongness must be preserved across IC patching.
+  DCHECK(LoadICState::GetStrength(code->extra_ic_state()) ==
+         LoadICState::GetStrength(target()->extra_ic_state()));
 
   IC::set_target(code);
 }