Commented Unassigned: PageRequestManager$_doPostBack does not evaluate the postBackElement correctly [27515]

After upgrading from .NET 3.5 to 4.5 there is a problem that the 'postBackSettings' are not correctly evaluated in the 'PageRequestManager$_doPostBack' method (MicrosoftAjaxWebForms.debug.js and MicrosoftAjaxWebForms.js)

The reason for this problem is that the script uses the 'clientID' of the appropriate control instead of the 'eventTarget' to check if it contains the 'masterPageUniqueID':
```
if (!postBackElement && mpUniqueID) {
if (clientID.indexOf(mpUniqueID + "$") === 0) {
postBackElement = document.getElementById(clientID.substr(mpUniqueID.length + 1));
}
}
```
AjaxControlToolkit version: 4.5.7.725

The script appears to have been copied from a .NET 4.0 release of ASP.NET in 2010 and is now no longer up-to-date. This could also be related to this issue here:
[https://connect.microsoft.com/VisualStudio/feedback/details/596088/](https://connect.microsoft.com/VisualStudio/feedback/details/596088/)

Maybe it is possible to simply switch back to using the official Script provided by ASP.NET instead of overriding it in the ControlToolKit?
Comments: Would you provide a sample project that illustrates the described problem?