Don't force representations in the loop builder.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 5fae5f72237cc824f27bae036f158a0df0ebed92..d3f1a9e09024c8f1643eb53bddc3b595b3953d3e 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -2498,8 +2498,10 @@ void HCompareIDAndBranch::InferRepresentation(HInferRepresentation* h_infer) {
   Representation observed_left = observed_input_representation(0);
   Representation observed_right = observed_input_representation(1);
 
-  Representation rep = Representation::Smi();
-  if (observed_left.IsInteger32() && observed_right.IsInteger32()) {
+  Representation rep = Representation::None();
+  rep = rep.generalize(observed_left);
+  rep = rep.generalize(observed_right);
+  if (rep.IsNone() || rep.IsSmiOrInteger32()) {
     if (!left_rep.IsTagged()) rep = rep.generalize(left_rep);
     if (!right_rep.IsTagged()) rep = rep.generalize(right_rep);
   } else {