[turbofan] CheckedTaggedToInt32 doesn't distinguish undefined and hole.

R=mvstanton@chromium.org
BUG=v8:5267

Review-Url: https://codereview.chromium.org/2397253002
Cr-Commit-Position: refs/heads/master@{#40073}

src/compiler/simplified-operator-reducer.cc

@@ -126,6 +126,7 @@ Reduction SimplifiedOperatorReducer::Reduce(Node* node) {
       }
       break;
     }
+    case IrOpcode::kCheckedTaggedToInt32:
     case IrOpcode::kCheckedTaggedSignedToInt32: {
       NodeMatcher m(node->InputAt(0));
       if (m.IsConvertTaggedHoleToUndefined()) {