Replace boolean indications of strict mode by an enum value.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 29ce51f36d051d07fd822d6902b578b131b3b347..8e14b51a2b5b6d6d4263eedd2310e75a99e0e3c2 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -11660,7 +11660,7 @@ MaybeObject* CompilationCacheTable::PutEval(String* src,
                                             SharedFunctionInfo* value) {
   StringSharedKey key(src,
                       context->closure()->shared(),
-                      value->strict_mode() ? kStrictMode : kNonStrictMode);
+                      value->strict_mode_flag());
   Object* obj;
   { MaybeObject* maybe_obj = EnsureCapacity(1, &key);
     if (!maybe_obj->ToObject(&obj)) return maybe_obj;