Roll ICU to 45f655f

https://chromium.googlesource.com/chromium/deps/icu.git/+log/834113a..45f655f

45f655f Cherry-pick: UnicodeSet performance enhancement
d2afb05 Delete another empty block after trim data

TBR=ftang@chromium.org,gsathya@chromium.org

Bug: 899983,901532,v8:8414
Test: Android webview start-up perf
Test: v8: intl/regress-8414.js
Change-Id: Ibc3e84fb26c4b3a158823e9ce6cee709b3161da7
Reviewed-on: https://chromium-review.googlesource.com/c/1325564
Commit-Queue: Jungshik Shin <jshin@chromium.org>
Reviewed-by: Jungshik Shin <jshin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606705}

DEPS

@@ -821,7 +821,7 @@ deps = {
     Var('chromium_git') + '/chromium/deps/hunspell_dictionaries.git' + '@' + 'a9bac57ce6c9d390a52ebaad3259f5fdb871210e',
 
   'src/third_party/icu':
-    Var('chromium_git') + '/chromium/deps/icu.git' + '@' + '834113aab5c1e5647690f93d9ae25f724095dd40',
+    Var('chromium_git') + '/chromium/deps/icu.git' + '@' + '45f655f2feb7069a7b9b47d1b1a596807bfd4220',
 
   'src/third_party/icu4j': {
       'packages': [