Replace BuildFastElementAccess() with AddFastElementAccess().

Replace BuildFastElementAccess() with AddFastElementAccess().

This is trivial cleanup. All calls to BuildFastElementAccess() pass
the result to AddInstruction().

R=svenpanne@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=15789

[Sven Panne, 2013-07-22 06:57:33]

LGTM. Nevertheless, we used to have some naming conventions in hydrogen.{cc,h}
regarding Add*/Build*/Handle*Try* methods, but things are very inconsistent
nowadays. Perhaps some bigger cleanup might be appropriate.

[Benedikt Meurer, 2013-07-22 07:00:56]

Committed patchset #1 manually as r15789 (presubmit successful).