Turns any of the header shapes a caller can hand to fetch/XHR into a plain
object keyed by header name. Headers instances and [name, value] arrays
have no own enumerable properties, so spreading them (which is what the
header sanitizer does) silently produced {} and dropped every header.
Turns any of the header shapes a caller can hand to fetch/XHR into a plain object keyed by header name.
Headersinstances and[name, value]arrays have no own enumerable properties, so spreading them (which is what the header sanitizer does) silently produced{}and dropped every header.