Intrinsics in the INLINE_FUNCTION_LIST are now avaliable without '_', too.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index d735a6b04fc66ddb8d7212d8e8e26a6820e27afa..475b9ffeb03f692df2671f075918534812902783 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -2320,10 +2320,8 @@ HValue* HGraphBuilder::BuildUncheckedStringAdd(
     {
       // Fallback to the runtime to add the two strings.
       Add<HPushArguments>(left, right);
-      Push(Add<HCallRuntime>(
-            isolate()->factory()->empty_string(),
-            Runtime::FunctionForId(Runtime::kStringAdd),
-            2));
+      Push(Add<HCallRuntime>(isolate()->factory()->empty_string(),
+                             Runtime::FunctionForId(Runtime::kStringAddRT), 2));
     }
     if_sameencodingandsequential.End();
   }