update ref impl and webidl

reference-implementation/lib/WritableStreamDefaultController-impl.js

@@ -5,9 +5,6 @@ const { AbortSteps, ErrorSteps } = require('./abstract-ops/internal-methods.js')
 const { ResetQueue } = require('./abstract-ops/queue-with-sizes.js');
 
 exports.implementation = class WritableStreamDefaultControllerImpl {
-  get abortReason() {
-    return this._abortReason;
-  }
   get signal() {
     return this._abortController.signal;
   }

reference-implementation/lib/WritableStreamDefaultController.webidl

@@ -1,6 +1,5 @@
 [Exposed=(Window,Worker,Worklet)]
 interface WritableStreamDefaultController {
-  readonly attribute any abortReason;
   readonly attribute AbortSignal signal;
   void error(optional any e);
 };

reference-implementation/lib/abstract-ops/writable-streams.js

@@ -107,7 +107,6 @@ function WritableStreamAbort(stream, reason) {
   if (stream._state === 'closed' || stream._state === 'errored') {
     return promiseResolvedWith(undefined);
   }
-  stream._controller._abortReason = reason;
   stream._controller._abortController.abort();
   const state = stream._state;
   if (state === 'closed' || state === 'errored') {
@@ -542,7 +541,6 @@ function SetUpWritableStreamDefaultController(stream, controller, startAlgorithm
   controller._queueTotalSize = undefined;
   ResetQueue(controller);
 
-  controller._abortReason = undefined;
   controller._abortController = new AbortController();
   controller._started = false;