Do not define use_icu_data_file_flag.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index b55e5639a0e542d22143be85bde8096d1408c6e3..b08fbb8efa0a22c805283e4240d2742fbd6cabe8 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -18,10 +18,6 @@ import("//build_overrides/v8.gni")
 import("snapshot_toolchain.gni")
 
 declare_args() {
-  # Use ICU data file (icudtl.dat) if true or library (shared on windows,
-  # static otherwise).
-  icu_use_data_file_flag = true
-
   # Enable the snapshot feature, for fast context creation.
   # http://v8project.blogspot.com/2015/09/custom-startup-snapshots.html
   v8_use_snapshot = true
@@ -1839,14 +1835,6 @@ v8_source_set("v8_base") {
     if (is_win) {
       deps += [ "//third_party/icu:icudata" ]
     }
-

[Michael Achenbach, 2016/05/19 14:56:25]

Is ICU exporting this as a public config now? E.g. will the defines be set for
the v8 targets as well?

[altimin, 2016/05/19 15:03:45]

Yes:
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/icu/BU...

-    if (icu_use_data_file_flag) {
-      defines += [ "ICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_FILE" ]
-    } else if (is_win) {
-      defines += [ "ICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_SHARED" ]
-    } else {
-      defines += [ "ICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_STATIC" ]
-    }
   } else {
     sources -= [
       "src/i18n.cc",