Checks Edge support for streams.

src/shared/streams_polyfill.js

@@ -13,7 +13,22 @@
  * limitations under the License.
  */
 
+let isReadableStreamSupported = false;
 if (typeof ReadableStream !== 'undefined') {
+  // MS Edge may say it has ReadableStream but they are not up to spec yet.
+  try {
+    // eslint-disable-next-line no-new
+    new ReadableStream({
+      start(controller) {
+        controller.close();
+      },
+    });
+    isReadableStreamSupported = true;
+  } catch (e) {
+    // The ReadableStream constructor cannot be used.
+  }
+}
+if (isReadableStreamSupported) {
   exports.ReadableStream = ReadableStream;
 } else {
   if (typeof PDFJSDev !== 'undefined' && PDFJSDev.test('CHROME')) {