Removed apiutils.h and related cleanup.

Removed apiutils.h and related cleanup.

ExtensionConfiguration is just a simple container for extension names
(in a perfect world we would use vector<string> and range-based for
loops), and HandleScopeData was in the totally wrong place. Some
additional cleanup on the way, e.g. using the null pattern behind our
external API.

R=dcarney@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=18632

[dcarney, 2014-01-15 15:04:52]

lgtm

[Sven Panne, 2014-01-16 08:17:51]

Committed patchset #2 manually as r18632 (presubmit successful).