Rails 4 adds an extra layer of "default" headers that override any that are missing (or deleted). This was breaking embedded shopfront responses.
Fixes:
74) setting response headers for embedded shopfronts with embedded shopfronts enabled with a valid whitelist allows iframes on certain pages when enabled in configuration
Failure/Error: expect(response.headers['X-Frame-Options']).to be_nil
expected: nil
got: "SAMEORIGIN"
# ./spec/requests/embedded_shopfronts_headers_spec.rb:54:in `block (4 levels) in <top (required)>'
75) setting response headers for embedded shopfronts with embedded shopfronts enabled with www prefix matches the URL structure in the header
Failure/Error: expect(response.headers['X-Frame-Options']).to be_nil
expected: nil
got: "SAMEORIGIN"
# ./spec/requests/embedded_shopfronts_headers_spec.rb:75:in `block (4 levels) in <top (required)>'
