Use gulp-terser instead of webpack-terser (#5788)

build-scripts/webpack.js

@@ -29,7 +29,7 @@ const createWebpackConfig = ({
   }
   return {
     mode: isProdBuild ? "production" : "development",
-    devtool: isProdBuild ? "source-map" : "inline-cheap-module-source-map",
+    devtool: isProdBuild ? undefined : "inline-cheap-module-source-map",
     entry,
     module: {
       rules: [
@@ -54,17 +54,18 @@ const createWebpackConfig = ({
     },
     optimization: {
       minimizer: [
-        new TerserPlugin({
-          cache: true,
-          parallel: true,
-          extractComments: true,
-          sourceMap: true,
-          terserOptions: {
-            safari10: true,
-            ecma: latestBuild ? undefined : 5,
-          },
-        }),
-      ],
+        // We minify in gulp. Only minify if we look at stats.
+        isStatsBuild &&
+          new TerserPlugin({
+            cache: true,
+            parallel: true,
+            extractComments: true,
+            terserOptions: {
+              safari10: true,
+              ecma: latestBuild ? undefined : 5,
+            },
+          }),
+      ].filter(Boolean),
     },
     plugins: [
       new ManifestPlugin(),