jQuery ajax BUG：object doesn't support this property or method

问题：jQuery控件的一个BUG

使用$.ajax时出现的错误，IE7下才会出错，IE6,IE8都正常。错误提示如下图：

官方论坛上的说明：

http://forum.jquery.com/topic/object-doesn-t-support-this-property-or-method-from-jquery-1-4-1-in-ie7-only
http://dev.jquery.com/ticket/6498
http://dev.jquery.com/ticket/6314

解决方案：
修改jquery-1.4.2.js。

论坛上有人提出的修改方式，我测试过可行。

Hi, I found this seems to relate to jQuery bug 6314 (http://dev.jquery.com/ticket/6314). In IE7, if "Enable native XMLHTTP support" is checked (under Tools >  Internet Options > Advanced tab > inside the security section) then this error shows up. Unchecking/disabiling the option seems to resolve the error.

However, since I cannot tell all website viewers to uncheck that option, then the following code also seems to resolve the issue:
In non-minified jQuery, find  the lines:
try {
  var oldAbort = xhr.abort;
  xhr.abort = function() {
    if ( xhr) {
      oldAbort.call( xhr );
    }

    onreadystatechange( "abort" );
  };
} catch(e) { }

replace it with the following code:
try {
  var oldAbort = xhr.abort;
  xhr.abort = function() {
    if ( xhr) {
      if (oldAbort.call === undefined) {
        oldAbort();
      } else {
        oldAbort.call( xhr );
      }
    }

    onreadystatechange( "abort" );
  };
} catch(e) { }

I believe the issue is as stated by other users in this forum, that the xhr (XMLHTTP) object is a native IE object, so the abort function on the xhr.abort function does not support call.