Additional supported languages on Chrome on iOS.

iOS system, Chrome itself and all of the third-party libraries
supports those locales, so pack them when building with gn.

BUG=625667

Review-Url: https://codereview.chromium.org/2133223002
Cr-Original-Commit-Position: refs/heads/master@{#405121}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 329e5137e45f52d2fcf9c94d6aafbcd9c4bf94d2

config/locales.gni

@@ -9,19 +9,15 @@
 if (is_ios) {
   ios_unsupported_locales = [
     "am",
-    "bg",
     "bn",
     "et",
-    "fa",
     "fil",
     "gu",
     "kn",
-    "lt",
     "lv",
     "ml",
     "mr",
     "sl",
-    "sr",
     "sw",
     "ta",
     "te",