fix editor in Firefox 78 ESR

manifest.json

@@ -86,6 +86,7 @@
 		"lib/single-file-extension-editor-helper.js",
 		"lib/single-file-zip.min.js",
 		"lib/single-file-z-worker.js",
+		"lib/web-stream.js",
 		"src/lib/readability/Readability.js",
 		"src/lib/readability/Readability-readerable.js",
 		"src/ui/pages/editor-note-web.css",

src/ui/pages/editor.html

@@ -68,8 +68,9 @@
 		</div>
 	</div>
 	<iframe class="editor"
-		srcdoc="&lt;!DOCTYPE html&gt;&lt;body&gt;&lt;script src=/lib/single-file-extension-editor-helper.js&gt;&lt;/script&gt;&lt;script src=/lib/single-file-extension-editor.js&gt;&lt;/script&gt;&lt;script src=/src/lib/readability/Readability.js&gt;&lt;/script&gt;&lt;script src=/src/lib/readability/Readability-readerable.js&gt;&lt;/script&gt;&lt;/body&gt;"
+		srcdoc="&lt;!DOCTYPE html&gt;&lt;body&gt;&lt;script src=/lib/web-stream.js&gt;&lt;/script&gt;&lt;script src=/lib/single-file-extension-editor-helper.js&gt;&lt;/script&gt;&lt;script src=/lib/single-file-extension-editor.js&gt;&lt;/script&gt;&lt;script src=/src/lib/readability/Readability.js&gt;&lt;/script&gt;&lt;script src=/src/lib/readability/Readability-readerable.js&gt;&lt;/script&gt;&lt;/body&gt;"
 		sandbox="allow-scripts allow-modals allow-downloads"></iframe>
+	<script src="/lib/web-stream.js"></script>
 	<script src="/lib/chrome-browser-polyfill.js"></script>
 	<script src="/lib/single-file.js"></script>
 	<script type="module" src="/src/ui/bg/ui-editor.js"></script>