POST data not sent in IE 11 using the WebBrowser control - xmlhttprequest

Question

I have the following JavaScript code being executed inside of an onclick event handler on my website.
var newRequest = new window.XMLHttpRequest();
newRequest.open('POST', '/index.cfm', true);
newRequest.send('q');
If I use IE 11 and open up my web page that is located on a testing server I can see that the request gets sent as expected using Fiddler with a content length of 1 and 'q' in the post data. However, if I open up my application that hosts the WebBrowser control and navigate to the same website on my test server and have it execute the above code I can always see that the request is being made but that the Content-Length header is 0 and 'q' is not sent along with the request. Here is the failing request as it appears in Fiddler.
POST http://test.mycompany.com/index.cfm HTTP/1.1
Accept: */*
Referer: http://test.mycompany.com/Curtis/BrowserTests/BrowserEventTests.html
Accept-Language: en-US
Content-Type: text/plain;charset=UTF-8
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko
Host: test.mycompany.com
Content-Length: 0
Connection: Keep-Alive
Pragma: no-cache
If I then set the HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION registry value for my executable to 9000 then it works and does send the post data as expected.
Here is the correct request as reported by Fiddler.
POST http://test.mycompany.com/index.cfm HTTP/1.1
Accept: */*
Referer: http://test.mycompany.com/Curtis/BrowserTests/BrowserEventTests.html
Accept-Language: en-us
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko
Host: test.mycompany.com
Content-Length: 1
Connection: Keep-Alive
Pragma: no-cache
q
If I change that value back to 10000 or 11000 then it does not work. Does anyone have any ideas on why the post data would not be sent properly using the WebBrowser control? I have reset my IE settings back to factory default with no change in behavior.
Update: If I change the JavaScript to look like this instead then it works with the emulation mode set to 10000.
var newRequest = new ActiveXObject("Msxml2.XMLHTTP");
newRequest.open('POST', '/index.cfm', true);
newRequest.send('q');
Is this just a bug that needs to be reported?