Clean up recent string conversion function changes, part 1: Remove unnecessar...

Clean up recent string conversion function changes, part 1: Remove unnecessary code.  Thanks to a change in escape.cc I can basically revert the ICU conversions back to what they used to be; I can also get rid of half the conversions immediately since they aren't used.

This does not split out the "adjust" versions of the UTF conversions into their own header/implementation; that's coming in the next patch.

BUG=4010
TEST=none

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=31533

[Peter Kasting, 2009-11-09 23:56:45]

Note: I removed the comments above the ICU function definitions because Scott
pointed out in my previous review that we already had comments in the header
that were probably better anyway, and I meant to remove all four but only did
one then.

[brettw, 2009-11-10 01:11:26]

LGTM