feat: extension support (#78)

pkg/download/engine/polyfill/package.json

@@ -0,0 +1,22 @@
+{
+  "name": "polyfill",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "type": "module",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "dev": "webpack --mode production --watch",
+    "build": "webpack --mode production"
+  },
+  "author": "",
+  "license": "ISC",
+  "devDependencies": {
+    "webpack": "^5.75.0",
+    "webpack-cli": "^5.0.1"
+  },
+  "dependencies": {
+    "blob-polyfill": "^7.0.20220408",
+    "whatwg-fetch": "^3.6.2"
+  }
+}