[strong] Implement strong mode restrictions on property access

src/messages.h

Index: src/messages.h
diff --git a/src/messages.h b/src/messages.h
index 985e794760a7a565fb3e500fb8a661de3bbf746e..33c4f5c5e5c6d9932e4bdd5cf9b7fe00234dbb79 100644
--- a/src/messages.h
+++ b/src/messages.h
@@ -373,6 +373,8 @@ class CallSite {
     "instead")                                                                 \
   T(StrongForIn,                                                               \
     "In strong mode, 'for'-'in' loops are deprecated, use 'for'-'of' instead") \
+  T(StrongPropertyAccess,                                                      \
+    "In strong mode, accessing missing property '%' of % is deprecated")       \
   T(StrongSuperCallDuplicate,                                                  \
     "In strong mode, invoking the super constructor multiple times is "        \
     "deprecated")                                                              \