Crash with an error message when ICU data files are missing

Before, we'd just crash.

BUG=v8:3348
R=svenpanne@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/807313003

Cr-Commit-Position: refs/heads/master@{#25877}

src/i18n.cc

@@ -704,6 +704,10 @@ icu::SimpleDateFormat* DateFormat::InitializeDateTimeFormat(
     icu::Locale no_extension_locale(icu_locale.getBaseName());
     date_format = CreateICUDateFormat(isolate, no_extension_locale, options);
 
+    if (!date_format) {
+      FATAL("Failed to create ICU date format, are ICU data files missing?");
+    }
+
     // Set resolved settings (pattern, numbering system, calendar).
     SetResolvedDateSettings(
         isolate, no_extension_locale, date_format, resolved);
@@ -780,6 +784,10 @@ icu::DecimalFormat* NumberFormat::InitializeNumberFormat(
     number_format = CreateICUNumberFormat(
         isolate, no_extension_locale, options);
 
+    if (!number_format) {
+      FATAL("Failed to create ICU number format, are ICU data files missing?");
+    }
+
     // Set resolved settings (pattern, numbering system).
     SetResolvedNumberSettings(
         isolate, no_extension_locale, number_format, resolved);
@@ -839,6 +847,10 @@ icu::Collator* Collator::InitializeCollator(
     icu::Locale no_extension_locale(icu_locale.getBaseName());
     collator = CreateICUCollator(isolate, no_extension_locale, options);
 
+    if (!collator) {
+      FATAL("Failed to create ICU collator, are ICU data files missing?");
+    }
+
     // Set resolved settings (pattern, numbering system).
     SetResolvedCollatorSettings(
         isolate, no_extension_locale, collator, resolved);
@@ -898,6 +910,10 @@ icu::BreakIterator* BreakIterator::InitializeBreakIterator(
     break_iterator = CreateICUBreakIterator(
         isolate, no_extension_locale, options);
 
+    if (!break_iterator) {
+      FATAL("Failed to create ICU break iterator, are ICU data files missing?");
+    }
+
     // Set resolved settings (locale).
     SetResolvedBreakIteratorSettings(
         isolate, no_extension_locale, break_iterator, resolved);