Add corelib tests

test/codegen/corelib/int_truncate_to_double_test.dart

+// Copyright (c) 2013, 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.
+
+import 'package:expect/expect.dart';
+
+main() {
+  Expect.equals(0.0, 0.truncateToDouble());
+  Expect.equals(1.0, 1.truncateToDouble());
+  Expect.equals(0x1234, 0x1234.truncateToDouble());
+  Expect.equals(0x12345678, 0x12345678.truncateToDouble());
+  Expect.equals(0x123456789AB, 0x123456789AB.truncateToDouble());
+  Expect.equals(81985529216486900.0, 0x123456789ABCDEF.truncateToDouble());
+  Expect.equals(
+      2.7898229935051914e+55,
+      0x123456789ABCDEF0123456789ABCDEF0123456789ABCDEF.truncateToDouble());
+  Expect.equals(-1.0, -1.truncateToDouble());
+  Expect.equals(-0x1234, -0x1234.truncateToDouble());
+  Expect.equals(-0x12345678, -0x12345678.truncateToDouble());
+  Expect.equals(-0x123456789AB, -0x123456789AB.truncateToDouble());
+  Expect.equals(-81985529216486900.0, -0x123456789ABCDEF.truncateToDouble());
+  Expect.equals(
+      -2.7898229935051914e+55,
+      -0x123456789ABCDEF0123456789ABCDEF0123456789ABCDEF.truncateToDouble());
+
+  Expect.isTrue(0.truncateToDouble() is double);
+  Expect.isTrue(1.truncateToDouble() is double);
+  Expect.isTrue(0x1234.truncateToDouble() is double);
+  Expect.isTrue(0x12345678.truncateToDouble() is double);
+  Expect.isTrue(0x123456789AB.truncateToDouble() is double);
+  Expect.isTrue(0x123456789ABCDEF.truncateToDouble() is double);
+  Expect.isTrue(
+      0x123456789ABCDEF0123456789ABCDEF0123456789ABCDEF.truncateToDouble()
+      is double);
+  Expect.isTrue(-1.truncateToDouble() is double);
+  Expect.isTrue(-0x1234.truncateToDouble() is double);
+  Expect.isTrue(-0x12345678.truncateToDouble() is double);
+  Expect.isTrue(-0x123456789AB.truncateToDouble() is double);
+  Expect.isTrue(-0x123456789ABCDEF.truncateToDouble() is double);
+  Expect.isTrue(
+      -0x123456789ABCDEF0123456789ABCDEF0123456789ABCDEF.truncateToDouble()
+      is double);
+}