Use es6 for client

Author: code-asher

packages/web/webpack.config.js

@@ -10,8 +10,7 @@ module.exports = merge(
 		entry: path.join(root, "packages/web/src/index.ts"),
 		template: path.join(root, "packages/web/src/index.html"),
 		typescriptCompilerOptions: {
-			"target": "es5",
-			"lib": ["dom", "esnext"],
+			"target": "es6",
 			"importHelpers": true,
 		},
 	},