Complete support has been added to enable use of DASH endpoints by browser-based javascript clients that would normally be constrained by cross-origin restrictions. The Azure Storage API (since API version 2013-08-15) enables support for Cross-Origin Resource Sharing (CORS) via calling the Set Blob Service Properties API (https://msdn.microsoft.com/en-us/library/azure/hh452235.aspx) and then the Preflight Blob Request OPTIONS (https://msdn.microsoft.com/en-us/library/azure/dn535599.aspx). Previous versions of DASH did not fully support setting the service properties which prevented the preflight request authorizing any hosts.
Additionally, explicit support has been added to enable XMLHttpRequest callers to indicate that they handle redirection responses issued by DASH by setting the x-ms-dash-client request header (the normal mechanism of updating the User-Agent header is unavailable to XHR callers).
A new integration test suite project has been added (derived from the Azure Storage CORS sample - https://code.msdn.microsoft.com/Windows-Azure-Storage-CORS-45e5ce76) to enable full regression testing of CORS support in future releases.