9aea080df4
This splits ReadableByteStreamControllerCommitPullIntoDescriptor from ReadableByteStreamControllerProcessPullIntoDescriptorsUsingQueue so that close/chunk steps will run only after processing all descriptors, thus preventing user JS from potentially modifying anything during the process. Corresponding to https://github.com/whatwg/streams/pull/1326 with some cleanup in https://github.com/whatwg/streams/pull/1336. Differential Revision: https://phabricator.services.mozilla.com/D232663