[compiler] Introduce code stubs for string relational comparisons.

src/code-factory.cc

Index: src/code-factory.cc
diff --git a/src/code-factory.cc b/src/code-factory.cc
index 79b2ea004c2e074f3385a3efa86d9d00d2642844..9015cbbff789a096edcdd64dc59a654f111ad6f9 100644
--- a/src/code-factory.cc
+++ b/src/code-factory.cc
@@ -257,6 +257,30 @@ Callable CodeFactory::StringNotEqual(Isolate* isolate) {
 }
 
 // static
+Callable CodeFactory::StringLessThan(Isolate* isolate) {
+  StringLessThanStub stub(isolate);
+  return Callable(stub.GetCode(), stub.GetCallInterfaceDescriptor());
+}
+
+// static
+Callable CodeFactory::StringLessThanOrEqual(Isolate* isolate) {
+  StringLessThanOrEqualStub stub(isolate);
+  return Callable(stub.GetCode(), stub.GetCallInterfaceDescriptor());
+}
+
+// static
+Callable CodeFactory::StringGreaterThan(Isolate* isolate) {
+  StringGreaterThanStub stub(isolate);
+  return Callable(stub.GetCode(), stub.GetCallInterfaceDescriptor());
+}
+
+// static
+Callable CodeFactory::StringGreaterThanOrEqual(Isolate* isolate) {
+  StringGreaterThanOrEqualStub stub(isolate);
+  return Callable(stub.GetCode(), stub.GetCallInterfaceDescriptor());
+}
+
+// static
 Callable CodeFactory::SubString(Isolate* isolate) {
   SubStringStub stub(isolate);
   return Callable(stub.GetCode(), stub.GetCallInterfaceDescriptor());