Optimistically hoist SmiCheck through phi when the only value of unknown type coming into the phi i…

tests/language/deopt_hoisted_smi_check.dart

+// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+// Test deoptimization caused by running code that did not collect type
+// feedback before.
+
+sum(a, b) {
+  int sum = 0;
+  for (int j = 1; j < 10; j++) {
+    for (int i = a; i < b; i++) {
+      sum++;
+    }
+  }
+  return sum;
+}
+
+main() {
+  for (var i = 0; i < 2000; i++) Expect.equals(9, sum(1, 2));
+  Expect.equals(9, sum(1.0, 2.0));  // Passing double causes deoptimization.
+}