Fixed typo - inconsistent notice for undefined property (introduced by fix for #49348)

The message added as a fix for #49348 (0c6d903ce7615a7197cb997d67d98058c3ec5d6a) is not consistent with the other one triggered in similar case.

Consider the following code:
```php
$x = new stdClass();
echo $x->foo++;
echo $x->bar;
```

Currently, it triggers two notices:
Notice: Undefined property: foo
Notice: Undefined property: stdClass::$bar

The first one was added by the fix for #49348 and is inconsistent with other notices related to property access. It should be same as the other one (should contain classname, :: and dollar).

(I already [commented](https://bugs.php.net/bug.php?id=49348#1364587653) on bugs.php.net and here in #281, but noone cared.)