Promote the current V8 benchmark suite candidate to version 6.

benchmarks/base.js

Index: benchmarks/base.js
===================================================================
--- benchmarks/base.js	(revision 5595)
+++ benchmarks/base.js	(working copy)
@@ -78,7 +78,7 @@
 // Scores are not comparable across versions. Bump the version if
 // you're making changes that will affect that scores, e.g. if you add
 // a new benchmark or change an existing one.
-BenchmarkSuite.version = '6 (candidate)';
+BenchmarkSuite.version = '6';
 
 
 // To make the benchmark results predictable, we replace Math.random