.giff rendering IE 11

// internal SharePoint 2010 - correctly renders the .giff
// response headers
HTTP/1.1 304 NOT MODIFIED
Cache-Control: private,max-age=0
Content-Length: 0
Expires: Wed, 28 Oct 2015 19:29:18 GMT
Server: Microsoft-IIS/7.5
X-Powered-By: ASP.NET
MicrosoftSharePointTeamServices: 14.0.0.4762
Date: Thu, 12 Nov 2015 19:29:18 GMT
// certain headers removed for brevity

// SharePoint O365 - will not render the .giff
// response headers
HTTP/1.1 304 Not Modified
Cache-Control: public, max-age=86400
Content-Length: 0
Accept-Ranges: bytes
Server: Microsoft-IIS/8.5
Strict-Transport-Security: max-age=31536000
X-FRAME-OPTIONS: SAMEORIGIN
X-Powered-By: ASP.NET
MicrosoftSharePointTeamServices: 16.0.0.4608
X-Content-Type-Options: nosniff
Date: Thu, 12 Nov 2015 19:26:47 GMT
// certain headers removed for brevity