Fix "gulp benchmark" for Windows

I'm presuming this task worked fine on Linux, but I use a Windows 10 laptop, and since Windows doesn't open extensionless files to check their shebang, this task failed.

Node.js on the other hand ignore's JavaScript files with a shebang, so this simple fix should make it work on all platforms now.

gulpfile.js

@@ -71,7 +71,7 @@ gulp.task("test", () =>
 
 // Run benchmarks.
 gulp.task("benchmark", () =>
-  spawn("benchmark/run", { stdio: "inherit" })
+  spawn("node", ["benchmark/run"], { stdio: "inherit" })
 );
 
 // Create the browser build.