Bump ICU to ece15d049f2d360721716089372e3749fb89e0f4. (#29313)

See b/203822961.

DEPS

diff --git a/DEPS b/DEPS
index 487526c..4124efa 100644
--- a/DEPS
+++ b/DEPS
@@ -152,7 +152,7 @@
    Var('chromium_git') + '/chromium/src/ios.git' + '@' + Var('ios_tools_revision'),
 
   'src/third_party/icu':
-   Var('chromium_git') + '/chromium/deps/icu.git' + '@' + 'a38aef9142ace942a8bf166020c569f4cda0f8d3',
+   Var('chromium_git') + '/chromium/deps/icu.git' + '@' + 'ece15d049f2d360721716089372e3749fb89e0f4',
 
   'src/third_party/khronos':
    Var('chromium_git') + '/chromium/src/third_party/khronos.git' + '@' + '7122230e90547962e0f0c627f62eeed3c701f275',