[turbofan] Add support for String.prototype.charCodeAt/charAt.

src/compiler/js-typed-lowering.cc

Index: src/compiler/js-typed-lowering.cc
diff --git a/src/compiler/js-typed-lowering.cc b/src/compiler/js-typed-lowering.cc
index b456516aa16e641493d28317300c1314a45a380a..acbeb78f7d9947e9661a613f3e6361ec41830a19 100644
--- a/src/compiler/js-typed-lowering.cc
+++ b/src/compiler/js-typed-lowering.cc
@@ -655,7 +655,11 @@ Reduction JSTypedLowering::ReduceJSComparison(Node* node) {
       r.OneInputCannotBe(Type::StringOrReceiver())) {
     const Operator* less_than;
     const Operator* less_than_or_equal;
-    if (hint != CompareOperationHints::kAny) {
+    if (r.BothInputsAre(Type::Signed32()) ||
+        r.BothInputsAre(Type::Unsigned32())) {
+      less_than = simplified()->NumberLessThan();
+      less_than_or_equal = simplified()->NumberLessThanOrEqual();
+    } else if (hint != CompareOperationHints::kAny) {
       less_than = simplified()->SpeculativeNumberLessThan(hint);
       less_than_or_equal = simplified()->SpeculativeNumberLessThanOrEqual(hint);
     } else if (r.BothInputsAre(Type::PlainPrimitive()) ||