Don't lose the expected precedence during && compilation.

tests/language/if_and_test.dart

+// Copyright (c) 2012, 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.
+
+// The "if (negative) res2 |= 3" below can be emitted as negative && (res2 |= 3)
+// in JavaScript. Dart2js produced the wrong output.
+
+_shiftRight(x, y) => x;
+int64_bits(x) => x;
+
+class A {
+  opshr(int n, a2) {
+    int res2;
+    bool negative = a2 === 496;
+
+    res2 = _shiftRight(a2, n);
+    if (negative) {
+      res2 |= 3;
+    }
+    return int64_bits(res2);
+  }
+}
+
+main() {
+  var a = new A();
+  var t;
+  for (int i = 0; i < 3; i++) {
+    t = a.opshr(99, 496);
+  }
+  Expect.equals(499, t);
+}