benchmark: fix punycode and get-ciphers benchmark

Add missing 'i=0' from for-loops from punycode and get-ciphers
benchmarks.

PR-URL: https://github.com/nodejs/node/pull/11720
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

benchmark/crypto/get-ciphers.js

@@ -18,6 +18,6 @@ function main(conf) {
       method();
   }
   bench.start();
-  for (; i < n; i++) method();
+  for (i = 0; i < n; i++) method();
   bench.end(n);
 }

benchmark/misc/punycode.js

@@ -46,7 +46,7 @@ function runPunycode(n, val) {
   for (; i < n; i++)
     usingPunycode(val);
   bench.start();
-  for (; i < n; i++)
+  for (i = 0; i < n; i++)
     usingPunycode(val);
   bench.end(n);
 }