Reset flag before processing a new chunk

Author: MattiasBuelens

index.bs

@@ -5295,6 +5295,7 @@ The following abstract operations support the implementation of the
 
  1. Let |stream| be |controller|.[=WritableStreamDefaultController/[[stream]]=].
  1. Perform ! [$WritableStreamMarkFirstWriteRequestInFlight$](|stream|).
+ 1. Set |controller|.[=WritableStreamDefaultController/[[releaseBackpressure]]=] to false.
  1. Let |sinkWritePromise| be the result of performing
     |controller|.[=WritableStreamDefaultController/[[writeAlgorithm]]=], passing in |chunk|.
  1. [=Upon fulfillment=] of |sinkWritePromise|,

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

@@ -704,6 +704,7 @@ function WritableStreamDefaultControllerProcessWrite(controller, chunk) {
   const stream = controller._stream;
 
   WritableStreamMarkFirstWriteRequestInFlight(stream);
+  controller._releaseBackpressure = false;
 
   const sinkWritePromise = controller._writeAlgorithm(chunk);
   uponPromise(