Do not set request's window

Per whatwg/fetch#1823, this concept is going away. After that change, null-client scenarios will automatically do the right thing, and create no user prompts, which aligns with this spec's desired outcome.

Author: domenic

index.bs

@@ -5025,8 +5025,6 @@ To <dfn>create a report request</dfn> given a [=URL=] |url| and a [=byte sequenc
     ::  `null`
     :   [=request/origin=]
     ::  |url|'s [=url/origin=]
-    :   [=request/window=]
-    ::  "`no-window`"
     :   [=request/service-workers mode=]
     ::  "`none`"
     :   [=request/initiator=]