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

runtime/bin/io.dart

Index: runtime/bin/io.dart
diff --git a/runtime/bin/io.dart b/runtime/bin/io.dart
index f673ee9cd495599e077c36198367900456a6d662..10b51dc749c932413d1f98a782714198fb841a29 100644
--- a/runtime/bin/io.dart
+++ b/runtime/bin/io.dart
@@ -9,6 +9,7 @@
 #library("io");
 #import("dart:coreimpl");
 #import("dart:isolate");
+#import("dart:math");
 #import("dart:nativewrappers");
 #import("dart:uri");
 #import("dart:crypto");