Rewrite some code in the x86-64 validator, speeding up the validator by nearly 15%.
Rewrite some code in the x86-64 validator, speeding up the validator by
nearly 15%.

Review URL: http://codereview.chromium.org/3347009

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@3194 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

nacl-webkit/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client,sbc100/native_client,nacl-webkit/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client,sbc100/native_client,nacl-webkit/native_client