LibJS: Throw in strict mode when assigning property to primitive value

Author: https://github.com/linusg
Commit: 8ff4587f65
Pull-request: https://github.com/SerenityOS/serenity/pull/2429

Libraries/LibJS/Runtime/Reference.cpp

@@ -50,6 +50,11 @@ void Reference::put(Interpreter& interpreter, Value value)
         return;
     }
 
+    if (!base().is_object() && interpreter.in_strict_mode()) {
+        interpreter.throw_exception<TypeError>(String::format("Can't assign property %s to primitive value", m_name.to_string().characters()));
+        return;
+    }
+
     auto* object = base().to_object(interpreter);
     if (!object)
         return;