Roll ICU to 715ec351 for Fuchsia build.

https://chromium.googlesource.com/chromium/deps/icu.git/+log/84fb34e2d..715ec351
715ec35 Do not use check_thin_archive in the Fuchsia build

TBR=jshin@chromium.org

Bug: fuchsia:61405
Change-Id: I6887abcc108c0e01a68d6b810318c5fad203ccd3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2477092Reviewed-by: Frank Tang <ftang@chromium.org>
Reviewed-by: Fabrice de Gans-Riberi <fdegans@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818766}

DEPS

@@ -1043,7 +1043,7 @@ deps = {
     Var('chromium_git') + '/chromium/deps/hunspell_dictionaries.git' + '@' + '18e09b9197a3b1d771c077c530d1a4ebad04c167',
 
   'src/third_party/icu':
-    Var('chromium_git') + '/chromium/deps/icu.git' + '@' + '84fb34e2d110871c3414183b9f6c0745453b02ad',
+    Var('chromium_git') + '/chromium/deps/icu.git' + '@' + '715ec351c0bcdd6b2d22f36e7d33b8e2ec519846',
 
   'src/third_party/icu4j': {
       'packages': [