Do not silently convert integers to doubles in binary operations. Only when at least one of argumen…

tests/language/double_int_addition_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.
+
+// Test that optimized code does not silently convert integers to doubles.
+
+
+main() {
+  // Optimize add-op
+  for (int i = 0; i < 10000; i++) {
+    addOp(1.1, 2.1);
+  }
+  
+  Expect.isTrue(addOp(1.1, 2.1) is double);
+  Expect.isTrue(addOp(1, 2) is int);
+}
+
+addOp(a, b) => a + b;