webkit: Instead of doing a conversion just use string16().

webkit: Instead of doing a conversion just use string16().

See chromium-dev thread for reference:
https://groups.google.com/a/chromium.org/group/chromium-dev/browse_thread/thread/ec912e667c6fdec8#

After landing this patch there will be zero entries of ASCIIToUTF16("");

R=tony@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=135592

[tfarina, 2012-05-04 21:21:46]

The other patch is here http://codereview.chromium.org/10356025/

[tony, 2012-05-04 21:36:39]

LGTM