[strong] Implement strong mode semantics for the count operation.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index c021a3fa3f0a595ad9c38205ac52eb2b90b6b857..2843195e867747553d9b9805a9153bff93f0fbd2 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -3404,7 +3404,7 @@ void HCompareNumericAndBranch::InferRepresentation(
     // (false). Therefore, any comparisons other than ordered relational
     // comparisons must cause a deopt when one of their arguments is undefined.
     // See also v8:1434
-    if (Token::IsOrderedRelationalCompareOp(token_)) {
+    if (Token::IsOrderedRelationalCompareOp(token_) && !is_strong(strength())) {
       SetFlag(kAllowUndefinedAsNaN);
     }
   }