Deprecate Math object in corelib in favor of dart:math library.

pkg/i18n/lib/date_format_helpers.dart

Index: pkg/i18n/lib/date_format_helpers.dart
diff --git a/pkg/i18n/lib/date_format_helpers.dart b/pkg/i18n/lib/date_format_helpers.dart
index 62e48a8f7f9077ee1b6ab9d8b3c329eefe5a3f70..2ac21f6d0a82f3c34bc552bb09aa2ef98a5f97ff 100644
--- a/pkg/i18n/lib/date_format_helpers.dart
+++ b/pkg/i18n/lib/date_format_helpers.dart
@@ -87,7 +87,7 @@ class _Stream {
     if (contents is String) {
       result = contents.substring(
           index,
-          Math.min(index + howMany, contents.length));
+          min(index + howMany, contents.length));
     } else {
       // Assume List
       result = contents.getRange(index, howMany);
@@ -133,6 +133,6 @@ class _Stream {
     while (!atEnd() && (digitMatcher.hasMatch(peek()))) {
       digits.add(next().charCodeAt(0));
     }
-    return Math.parseInt(new String.fromCharCodes(digits));
+    return parseInt(new String.fromCharCodes(digits));
   }
-}
+}