Tweak emit for performance, unfortunately no let/const lowering

Author: jakebailey

Gulpfile.js

@@ -100,10 +100,12 @@ async function esbuild(entrypoint, outfile) {
         "--bundle",
         `--outfile=${outfile}`,
         "--platform=node",
-        "--target=node12",
+        "--target=node10", // Node 10; oldest benchmarker.
         "--sourcemap",
         "--external:./node_modules/*",
         "--conditions=require",
+        // "--supported:const-and-let=false", // Unfortunately, no: https://github.com/evanw/esbuild/issues/297
+        "--supported:object-rest-spread=false", // See: https://github.com/evanw/esbuild/releases/tag/v0.14.46
     ]);
 }