Bug 1895198 - Add ExplicitSetUploadStreamLength to HttpChannelChild and move LoadWasOpened assert r=valentin,necko-reviewers

Differential Revision: https://phabricator.services.mozilla.com/D209521

netwerk/protocol/http/HttpBaseChannel.cpp

@@ -1319,8 +1319,6 @@ void HttpBaseChannel::ExplicitSetUploadStreamLength(
     return;
   }
 
-  // SetRequestHeader propagates headers to chrome if HttpChannelChild
-  MOZ_ASSERT(!LoadWasOpened());
   nsAutoCString contentLengthStr;
   contentLengthStr.AppendInt(aContentLength);
   SetRequestHeader(header, contentLengthStr, false);