Tests indicate that lookup in QHash<QString, ...> is more performant
even for short strings.

Change-Id: I8e5a73d0f1a72e202522f397b16901887f9c3591
Reviewed-on: http://codereview.qt-project.org/5070


Reviewed-by: Leandro T. C. Melo <leandro.melo@nokia.com>