Move print to corelib.

runtime/bin/builtin.dart

Index: runtime/bin/builtin.dart
diff --git a/runtime/bin/builtin.dart b/runtime/bin/builtin.dart
index d7f5974f96f8ef78caf40374e8b8e9d4e5cad60a..8e1b09d18139de2bfb3379fea87565071dd613c8 100644
--- a/runtime/bin/builtin.dart
+++ b/runtime/bin/builtin.dart
@@ -5,7 +5,8 @@
 #library("builtin");
 #import("dart:uri");
 
-void print(arg) {
+// Corelib 'print' implementation.
+void _print(arg) {
   _Logger._printString(arg.toString());
 }
 
@@ -13,6 +14,7 @@ class _Logger {
   static void _printString(String s) native "Logger_PrintString";
 }
 
+_getPrintClosure() => _print;
 
 // The URI that the entrypoint script was loaded from. Remembered so that
 // package imports can be resolved relative to it.