[v16.x backport] stream: implement streams to webstreams adapters

doc/api/stream.md

@@ -2080,7 +2080,7 @@ for performance reasons.
 
 ### `stream.Readable.fromWeb(readableStream[, options])`
 <!-- YAML
-added: v16.11.0
+added: REPLACEME
 -->
 
 > Stability: 1 - Experimental
@@ -2093,6 +2093,41 @@ added: v16.11.0
   * `signal` {AbortSignal}
 * Returns: {stream.Readable}
 
+### `stream.Readable.toWeb(streamReadable)`
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+* `streamReadable` {stream.Readable}
+* Returns: {ReadableStream}
+
+### `stream.Writable.fromWeb(writableStream[, options])`
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+* `writableStream` {WritableStream}
+* `options` {Object}
+  * `decodeStrings` {boolean}
+  * `highWaterMark` {number}
+  * `objectMode` {boolean}
+  * `signal` {AbortSignal}
+* Returns: {stream.Writable}
+
+### `stream.Writable.toWeb(streamWritable)`
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+* `streamWritable` {stream.Writable}
+* Returns: {WritableStream}
+
 ### `stream.Readable.isDisturbed(stream)`
 <!-- YAML
 added: v16.8.0
@@ -2133,6 +2168,37 @@ A utility method for creating duplex streams.
 * `Promise` converts into readable `Duplex`. Value `null` is ignored.
 * Returns: {stream.Duplex}
 
+### `stream.Duplex.fromWeb(pair[, options])`
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+* `pair` {Object}
+  * `readable` {ReadableStream}
+  * `writable` {WritableStream}
+* `options` {Object}
+  * `allowHalfOpen` {boolean}
+  * `decodeStrings` {boolean}
+  * `encoding` {string}
+  * `highWaterMark` {number}
+  * `objectMode` {boolean}
+  * `signal` {AbortSignal}
+* Returns: {stream.Duplex}
+
+### `stream.Duplex.toWeb(streamDuplex)`
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+* `streamDuplex` {stream.Duplex}
+* Returns: {Object}
+  * `readable` {ReadableStream}
+  * `writable` {WritableStream}
+
 ### `stream.addAbortSignal(signal, stream)`
 <!-- YAML
 added: v15.4.0

lib/internal/fs/promises.js

@@ -827,6 +827,8 @@ module.exports = {
     appendFile,
     readFile,
     watch,
+
+    kHandle,
   },
 
   FileHandle,

lib/internal/streams/duplex.js

@@ -117,3 +117,22 @@ Duplex.from = function(body) {
   }
   return duplexify(body, 'body');
 };
+
+let webStreamsAdapters;
+
+// Lazy to avoid circular references
+function lazyWebStreams() {
+  if (webStreamsAdapters === undefined)
+    webStreamsAdapters = require('internal/webstreams/adapters');
+  return webStreamsAdapters;
+}
+
+Duplex.fromWeb = function(pair, options) {
+  return lazyWebStreams().newStreamDuplexFromReadableWritablePair(
+    pair,
+    options);
+};
+
+Duplex.toWeb = function(duplex) {
+  return lazyWebStreams().newReadableWritablePairFromDuplex(duplex);
+};

lib/internal/streams/readable.js

@@ -1384,3 +1384,22 @@ Readable.wrap = function(src, options) {
     }
   }).wrap(src);
 };
+
+let webStreamsAdapters;
+
+// Lazy to avoid circular references
+function lazyWebStreams() {
+  if (webStreamsAdapters === undefined)
+    webStreamsAdapters = require('internal/webstreams/adapters');
+  return webStreamsAdapters;
+}
+
+Readable.fromWeb = function(readableStream, options) {
+  return lazyWebStreams().newStreamReadableFromReadableStream(
+    readableStream,
+    options);
+};
+
+Readable.toWeb = function(streamReadable) {
+  return lazyWebStreams().newStreamReadableFromReadableStream(streamReadable);
+};

lib/internal/streams/writable.js

@@ -871,3 +871,22 @@ Writable.prototype._destroy = function(err, cb) {
 Writable.prototype[EE.captureRejectionSymbol] = function(err) {
   this.destroy(err);
 };
+
+let webStreamsAdapters;
+
+// Lazy to avoid circular references
+function lazyWebStreams() {
+  if (webStreamsAdapters === undefined)
+    webStreamsAdapters = require('internal/webstreams/adapters');
+  return webStreamsAdapters;
+}
+
+Writable.fromWeb = function(writableStream, options) {
+  return lazyWebStreams().newStreamWritableFromWritableStream(
+    writableStream,
+    options);
+};
+
+Writable.toWeb = function(streamWritable) {
+  return lazyWebStreams().newWritableStreamFromStreamWritable(streamWritable);
+};