This adds a utils object meant specifically for V8 extras, presenting a limited
API surface for doing things that would otherwise require %-functions.

BUG=v8:4276
LOG=Y
R=jochen@chromium.org,yangguo@chromium.org

Review URL: https://codereview.chromium.org/1343113003

Cr-Commit-Position: refs/heads/master@{#30773}