[compiler] Introduce code stubs for string relational comparisons.

src/code-factory.h

Index: src/code-factory.h
diff --git a/src/code-factory.h b/src/code-factory.h
index 6431534872152ffeb3402de7af3380e6a26928e2..663e73ae3eb535f31458eaa86311da42494a4058 100644
--- a/src/code-factory.h
+++ b/src/code-factory.h
@@ -84,9 +84,13 @@ class CodeFactory final {
 
   static Callable StringAdd(Isolate* isolate, StringAddFlags flags,
                             PretenureFlag pretenure_flag);
-  static Callable StringCompare(Isolate* isolate);
+  static Callable StringCompare(Isolate* isolate, Token::Value token);
   static Callable StringEqual(Isolate* isolate);
   static Callable StringNotEqual(Isolate* isolate);
+  static Callable StringLessThan(Isolate* isolate);
+  static Callable StringLessThanOrEqual(Isolate* isolate);
+  static Callable StringGreaterThan(Isolate* isolate);
+  static Callable StringGreaterThanOrEqual(Isolate* isolate);
   static Callable SubString(Isolate* isolate);
 
   static Callable Typeof(Isolate* isolate);