[strong] Implement per-object restrictions behaviour of delete operator

src/messages.h

Index: src/messages.h
diff --git a/src/messages.h b/src/messages.h
index 75314e93f989fcd9d041f9679d4607d2b625bd11..7ea84dbcc563318e9b511646aee7111777c443ff 100644
--- a/src/messages.h
+++ b/src/messages.h
@@ -226,6 +226,8 @@ class CallSite {
   T(StrictReadOnlyProperty, "Cannot assign to read only property '%' of %")    \
   T(StrongArity,                                                               \
     "In strong mode, calling a function with too few arguments is deprecated") \
+  T(StrongDeleteProperty,                                                      \
+    "On strong object %, deletion of property % is deprecated")                \
   T(StrongImplicitCast, "In strong mode, implicit conversions are deprecated") \
   T(SymbolKeyFor, "% is not a symbol")                                         \
   T(SymbolToPrimitive,                                                         \