Activate packed array optimizations by default

R=jkummerow@chromium.org

Review URL: https://chromiumcodereview.appspot.com/10546123

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11778 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/flag-definitions.h

@@ -152,7 +152,7 @@ DEFINE_implication(harmony, harmony_collections)
 DEFINE_implication(harmony_modules, harmony_scoping)
 
 // Flags for experimental implementation features.
-DEFINE_bool(packed_arrays, false, "optimizes arrays that have no holes")
+DEFINE_bool(packed_arrays, true, "optimizes arrays that have no holes")
 DEFINE_bool(smi_only_arrays, true, "tracks arrays with only smi values")
 DEFINE_bool(clever_optimizations,
             true,