XmlHttpRequest.XmlHttpRequest() and XmlHttpRequest.getResponseHeader() return empty string even if XmlHttpRequest.responseHeaders returns an object

[joshzana]

Commit db330ac implemented XmlHttpRequest.responseHeaders as a field but failed to add the corresponding getter methods that are defined. This causes existing JS libraries that expect the methods to have incorrect behavior.

See https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest for the spec.

Example from debug session:

this.xhr.responseHeaders
Object {Content-Type: "text/javascript", Pragma: "no-cache", x-server-response-time: "45", Content-Encoding: "gzip", Server: "nginx"…}Cache-Control: "no-cache"Connection: "keep-alive"Content-Encoding: "gzip"Content-Type: "text/javascript"Date: "Thu, 16 Apr 2015 03:43:35 GMT"Pragma: "no-cache"Server: "nginx"Transfer-Encoding: "Identity"x-content-type-options:...
this.xhr.getAllResponseHeaders()
""
this.xhr.getResponseHeader()
""