Description:
------------
The interface of a parent class is also forced to be implemented on to the children classes if they use methods with same name as in Interface. Even though the parent class has implemented the methods declared in the Interface legally.

Reproduce code:
---------------
interface MyInterface {
   public function Z($s);
}

class MyClass implements MyInterface {
   public function Z($s) {}
}

class MySubClass extends MyClass {
   public function Z() {}
}


Expected result:
----------------
Above should be legal (at least i think), because parent is implementing the interface, the child is just extending the parent's method.

But, if we remove the method completely from child class, then there is no error message and Interface is no longer being forced on to child. This suggests inconsistency.

Also, if we remove the interface from the code, then the parent child extension of the same method name is still legal, as the number of arguments is not being checked anymore.

Actual result:
--------------
Fatal error: Declaration of MySubClass::Z() must be compatible with that of MyInterface::Z() in C:\httpd\PHPObject3.0\index.php on line 12