Port CallSite methods to C++.

The goal is to port all of error stack trace formatting to C++.
We will do this bottom up, by first porting helper functions.

Eventually, CallSite methods will only be used when a custom
error stack trace formatter is defined via Error.prepareStackTrace.

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/1060583008

Cr-Commit-Position: refs/heads/master@{#28095}