WIP on shimming streams in firefox

app/transformStream.js

@@ -0,0 +1,25 @@
+/* global TransformStream */
+import { createReadableStreamWrapper } from '@mattiasbuelens/web-streams-adapter';
+import { TransformStream as TransformStreamPony } from 'web-streams-ponyfill';
+
+const toNative = createReadableStreamWrapper(ReadableStream);
+
+class TransformStreamLocal {
+  constructor(transformer) {
+    this.stream = new TransformStreamPony(transformer);
+    this.local = true;
+  }
+  get nativeReadable() {
+    return toNative(this.stream.readable);
+  }
+  get readable() {
+    return this.stream.readable;
+  }
+  get writable() {
+    return this.stream.writable;
+  }
+}
+
+export default (typeof TransformStream === 'function'
+  ? TransformStream
+  : TransformStreamLocal);