Check comparison tag before checking attributes in IfThenElseInstr::AttributesEqual.

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
diff --git a/runtime/vm/intermediate_language.h b/runtime/vm/intermediate_language.h
index 876a015020e4c08416a878efba78cb993308cd84..0a408487a340bd03e16b585b7eccd342a4c0fbe5 100644
--- a/runtime/vm/intermediate_language.h
+++ b/runtime/vm/intermediate_language.h
@@ -3194,7 +3194,8 @@ class IfThenElseInstr : public Definition {
   }
   virtual bool AttributesEqual(Instruction* other) const {
     IfThenElseInstr* other_if_then_else = other->AsIfThenElse();
-    return comparison()->AttributesEqual(other_if_then_else->comparison()) &&
+    return (comparison()->tag() == other_if_then_else->comparison()->tag()) &&
+           comparison()->AttributesEqual(other_if_then_else->comparison()) &&
            (if_true_ == other_if_then_else->if_true_) &&
            (if_false_ == other_if_then_else->if_false_);
   }