LibJS: Loosen type system

This commits makes effort towards tolerating some of javascript's quirks
when it comes to its type system, note that the interpreter's way of
handling type coercion is still not mature at all, for example, we still
have to implement NaN instead of just crashing when trying to parse a
string and failing.

Libraries/LibJS/Object.cpp

@@ -87,4 +87,34 @@ bool Object::has_own_property(const String& property_name) const
     return m_properties.get(property_name).has_value();
 }
 
+Value Object::to_primitive(PreferredType preferred_type) const
+{
+    Value result = js_undefined();
+
+    switch (preferred_type) {
+    case PreferredType::Default:
+    case PreferredType::Number: {
+        result = value_of();
+        if (result.is_object()) {
+            result = to_string();
+        }
+        break;
+    }
+    case PreferredType::String: {
+        result = to_string();
+        if (result.is_object())
+            result = value_of();
+        break;
+    }
+    }
+
+    ASSERT(!result.is_object());
+    return result;
+}
+
+Value Object::to_string() const
+{
+    return js_string(heap(), String::format("[object %s]", class_name()));
+}
+
 }