[builtins] Move StringLocaleCompare to a builtin.

src/builtins/builtins.h

Index: src/builtins/builtins.h
diff --git a/src/builtins/builtins.h b/src/builtins/builtins.h
index dd567199cc07f37fc4f709c442c13d2b0d671d25..844af263179e7d6d64d8154a992aeb73db4ded69 100644
--- a/src/builtins/builtins.h
+++ b/src/builtins/builtins.h
@@ -534,6 +534,8 @@ namespace internal {
   TFJ(StringPrototypeCharAt, 2)                                               \
   /* ES6 section 21.1.3.2 String.prototype.charCodeAt ( pos ) */              \
   TFJ(StringPrototypeCharCodeAt, 2)                                           \
+  /* ES6 section 21.1.3.10 String.prototype.localeCompare ( that ) */         \
+  CPP(StringPrototypeLocaleCompare)                                           \
   /* ES6 section 21.1.3.12 String.prototype.normalize ( [form] ) */           \
   CPP(StringPrototypeNormalize)                                               \
   /* ES6 section 21.1.3.25 String.prototype.toString () */                    \