[turbofan] Change number operations to handle Undefined as well.

src/compiler/representation-change.h

Index: src/compiler/representation-change.h
diff --git a/src/compiler/representation-change.h b/src/compiler/representation-change.h
index 24e28f399c9bcd4cc98b393515e738c05ef92a21..94d37d2589ed006018489a5a93bd7bfb83f2753b 100644
--- a/src/compiler/representation-change.h
+++ b/src/compiler/representation-change.h
@@ -31,6 +31,9 @@ class Truncation final {
   bool TruncatesToWord32() const {
     return LessGeneral(kind_, TruncationKind::kWord32);
   }
+  bool TruncatesToFloat64() const {
+    return LessGeneral(kind_, TruncationKind::kFloat64);
+  }
   bool TruncatesNaNToZero() {
     return LessGeneral(kind_, TruncationKind::kWord32) ||
            LessGeneral(kind_, TruncationKind::kBool);