Add a separate icu data file for ChromeOS

third_party/icu/README.chromium

 Name: ICU
 URL: http://site.icu-project.org/
 
 This directory contains the source code of ICU 4.2.1 for C/C++
 
 1. It was obtained with the following:
 
     $ svn export --native-eol LF http://source.icu-project.org/repos/icu/icu/tags/release-4-2-1 icu42
 
 2. The following directories were removed because they're not used by Chromium
@@ skipping 114 matching lines @@
       linux needs the '@' in the preamble changed to '%'. See
       http://codereview.chromium.org/215026.
       mac/icudt42l_dat.s needs one line added after it is generated.  A
       .private_extern directive needs to be added so that the top of the
       file looks like:
 
 .globl _icudt42_dat
         .private_extern _icudt42_dat
         .data
 
+    - cros/icudt42l_dat.s : Built on Linux with
+      abriged locale source files in cros/locales put
+      in source/data/locales. Those abridged locales files are
+      for locales ChromeOS is not localized to. '@' in the preamble
+      is replaced with '%' as in linux.
+
 12. The header files were moved as shown below:
 
    source/common/unicode ==> public/common/unicode
    source/i18n/unicode   ==> public/i18n/unicode
 
 13. The patch for a memory leak in i18n/timezone.cpp (Windows only):
     see http://bugs.icu-project.org/trac/ticket/7135
 
     - patches/tzmemory.patch
 
 14. The patch for a crash in common/putil.c (Linux only):
     see http://bugs.icu-project.org/trac/ticket/7177
 
     - patches/linuxtz.patch
 
 15. The patch for Linux locale detection
 
     - patches/locdet.patch
 
 16. Merge the upstream change to get rid of a few compiler warnings
 
     - patches/remove_warnings.patch