Roll ICU to c844075a..ae18d608

Two changes:

f5b27d17 Make CalendarAstronomer public
ae18d608 Fix a typo with astro.h

TBR=jshin@chromium.org
BUG=726654

Review-Url: https://codereview.chromium.org/2914933002
Cr-Commit-Position: refs/heads/master@{#476343}

DEPS

@@ -154,7 +154,7 @@ deps = {
     Var('chromium_git') + '/external/github.com/google/googletest.git' + '@' + '42bc671f47b122fad36db5eccbc06868afdf7862',
 
   'src/third_party/icu':
-    Var('chromium_git') + '/chromium/deps/icu.git' + '@' + 'c844075aa0f1758d04f9192825f1b1e7e607992e',
+    Var('chromium_git') + '/chromium/deps/icu.git' + '@' + 'ae18d60831126f902d778541495194380ff77fd8',
 
   'src/third_party/hunspell_dictionaries':
     Var('chromium_git') + '/chromium/deps/hunspell_dictionaries.git' + '@' + 'dc6e7c25bf47cbfb466e0701fd2728b4a12e79d5',