Tweak perf suite to use geometric mean and remove tests with high variability.

Former-commit-id: ce4ff88ee6be007b761bcf991c59f30f28880973

vendor/benchmark.js/README.md

@@ -100,7 +100,7 @@ suite.add('RegExp#test', function() {
   console.log(String(event.target));
 })
 .on('complete', function() {
-  console.log('Fastest is ' + _.pluck(this.filter('fastest'), 'name'));
+  console.log('Fastest is ' + this.filter('fastest').pluck('name'));
 })
 // run async
 .run({ 'async': true });