Updated webpack version for JS examples

Author: elizarov

js/example-frontend-js/npm/package.json

@@ -6,14 +6,14 @@
     "type": "git",
     "url": "https://github.com/Kotlin/kotlinx.coroutines.git"
   },
-  "dependencies": {
-    "webpack": "3.10.0",
-    "html-webpack-plugin": "2.30.1",
-    "style-loader": "0.19.1",
-    "css-loader": "0.28.7"
-  },
   "devDependencies": {
-    "webpack-dev-server": "2.9.7"
+    "webpack": "4.29.1",
+    "webpack-cli": "3.2.3",
+    "webpack-dev-server": "3.1.14",
+    "html-webpack-plugin": "3.2.0",
+    "uglifyjs-webpack-plugin": "2.1.1",
+    "style-loader": "0.23.1",
+    "css-loader": "2.1.0"
   },
   "scripts": {
     "bundle": "webpack",

js/example-frontend-js/npm/webpack.config.js

@@ -12,6 +12,7 @@ const path = require("path");
 const dist = path.resolve(__dirname, "dist");
 
 module.exports = {
+    mode: "production",
     entry: {
         main: "main"
     },