[turbofan] Some more cleanup on the intrinsics.

src/runtime/runtime-strings.cc

Index: src/runtime/runtime-strings.cc
diff --git a/src/runtime/runtime-strings.cc b/src/runtime/runtime-strings.cc
index dd4983e75f9abff268c1abfeedd170f2741dd9ad..bd4dd699b4576363f7232380b75653e20863fce1 100644
--- a/src/runtime/runtime-strings.cc
+++ b/src/runtime/runtime-strings.cc
@@ -1245,12 +1245,5 @@ RUNTIME_FUNCTION(Runtime_StringCharCodeAt) {
   return __RT_impl_Runtime_StringCharCodeAtRT(args, isolate);
 }
 
-
-RUNTIME_FUNCTION(Runtime_StringGetLength) {
-  HandleScope scope(isolate);
-  DCHECK(args.length() == 1);
-  CONVERT_ARG_HANDLE_CHECKED(String, s, 0);
-  return Smi::FromInt(s->length());
-}
 }  // namespace internal
 }  // namespace v8