chore: stub out browserslist an tr46 packages MONGOSH-1335 (#1397)

Both of these packages add nontrivial amounts of code
to our bundles without providing additional value to mongosh.

Therefore, we stub these out and save about 50 % of our bundle
size and shave off about 10 % of startup duration.

config/webpack.base.config.js

@@ -1,5 +1,7 @@
 'use strict';
+const path = require('path');
 const TerserPlugin = require('terser-webpack-plugin');
+const BundleAnalyzerPlugin = require('webpack-bundle-analyzer').BundleAnalyzerPlugin;
 
 /** @type import('webpack').Configuration */
 module.exports = {
@@ -14,7 +16,13 @@ module.exports = {
   },
 
   resolve: {
-    extensions: ['.ts', '.js']
+    extensions: ['.ts', '.js'],
+    alias: {
+      // Stub out particularly large dependencies that are unnecessary and/or
+      // only provide features that Node.js also provides out of the box.
+      browserslist: path.resolve(__dirname, '..', 'scripts', 'dummy-browserslist.js'),
+      tr46: path.resolve(__dirname, '..', 'scripts', 'tr46-stub.js')
+    }
   },
 
   optimization: {
@@ -44,4 +52,11 @@ module.exports = {
 
   node: false,
   target: 'node',
+
+  plugins: [
+    new BundleAnalyzerPlugin({
+      analyzerMode: 'static',
+      openAnalyzer: false
+    })
+  ]
 };

package.json

@@ -146,6 +146,7 @@
     "terser-webpack-plugin": "^4.2.3",
     "ts-loader": "^8.0.14",
     "webpack": "^5.75.0",
+    "webpack-bundle-analyzer": "^4.7.0",
     "webpack-cli": "^4.3.1",
     "webpack-merge": "^5.8.0"
   }

scripts/dummy-browserslist.js

@@ -0,0 +1,9 @@
+'use strict';
+// Babel has a dependency on browserslist (and in particular,
+// caniuse-lite through browserslist, which is a fairly large
+// npm package). However, the way in which we use babel does
+// not actually require browserslist support, so we can safely
+// stub this away.
+module.exports = () => {
+  throw new Error('browserslist not supported');
+};