Roll ICU to 407b393 from 45f655f

  https://chromium.googlesource.com/chromium/deps/icu.git/+log/45f655f..407b393

The following changes are included:

  407b393 Update IANA timezone db to 2018g
  797b7c7 Add more locale variants
  d13a96f Unicoset Perf fix #2
  ecae5c0 Adjust calendar locale data trimming on Andorid

The ICU data files for mobile platforms got smaller. For desktop,
the size got increased by ~59 kb for more locale variant support.

TBR=ftang@chromium.org

Bug: 473288,863749,899983,901532,v8:8432
Test: v8: intl/regress-8413*
Test: Android webview start-up perf and Windows perf graph
Test: See crbug.com/900232
Test: See ICU 407b393 CL description for tz test.
Change-Id: Id3ec92cbbe82275b120ffa9747e110db598905dc
Reviewed-on: https://chromium-review.googlesource.com/c/1341468
Commit-Queue: Jungshik Shin <jshin@chromium.org>
Reviewed-by: Jungshik Shin <jshin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609129}

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' + '@' + '45f655f2feb7069a7b9b47d1b1a596807bfd4220',
+    Var('chromium_git') + '/chromium/deps/icu.git' + '@' + '407b39301e71006b68bd38e770f35d32398a7b14',
 
   'src/third_party/icu4j': {
       'packages': [