Add JavaScript to benchmark runner.

benchmark/fib.js

@@ -0,0 +1,13 @@
+function fib(n) {
+  if (n < 2) return n;
+  return fib(n - 1) + fib(n - 2);
+}
+
+var start = process.hrtime();
+var i = 0;
+for (var i = 0; i < 5; i++) {
+  console.log(fib(30));
+}
+var elapsed = process.hrtime(start);
+elapsed = elapsed[0] + elapsed[1] / 1000000000;
+console.log("elapsed: " + elapsed);

benchmark/run_all

@@ -20,7 +20,8 @@ LANGUAGES = [
   ("wren",   "../build/Release/wren", ".wren"),
   ("lua",    "lua",                   ".lua"),
   ("python", "python",                ".py"),
-  ("ruby",   "ruby",                  ".rb")
+  ("ruby",   "ruby",                  ".rb"),
+  ("js",     "node",                  ".js")
 ]
 
 # How many times to run a given benchmark. Should be an odd number to get the