Fix unaligned access to TypedData from native code.

tests/language/vm/unaligned_float_access_literal_index_test.dart

+// Copyright (c) 2016, 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.
+// VMOptions=--optimization_counter_threshold=10 --no-background_compilation
+
+import 'dart:typed_data';
+import 'package:expect/expect.dart';
+
+unalignedFloat32() {
+  var bytes = new ByteData(64);
+  bytes.setFloat32(0, 16.25);
+  Expect.equals(16.25, bytes.getFloat32(0));
+  bytes.setFloat32(1, 32.125);
+  Expect.equals(32.125, bytes.getFloat32(1));
+  bytes.setFloat32(2, 16.25);
+  Expect.equals(16.25, bytes.getFloat32(2));
+  bytes.setFloat32(3, 32.125);
+  Expect.equals(32.125, bytes.getFloat32(3));
+}
+
+unalignedFloat64() {
+  var bytes = new ByteData(64);
+  bytes.setFloat64(0, 16.25);
+  Expect.equals(16.25, bytes.getFloat64(0));
+  bytes.setFloat64(1, 32.125);
+  Expect.equals(32.125, bytes.getFloat64(1));
+  bytes.setFloat64(2, 16.25);
+  Expect.equals(16.25, bytes.getFloat64(2));
+  bytes.setFloat64(3, 32.125);
+  Expect.equals(32.125, bytes.getFloat64(3));
+  bytes.setFloat64(4, 16.25);
+  Expect.equals(16.25, bytes.getFloat64(4));
+  bytes.setFloat64(5, 32.125);
+  Expect.equals(32.125, bytes.getFloat64(5));
+  bytes.setFloat64(6, 16.25);
+  Expect.equals(16.25, bytes.getFloat64(6));
+  bytes.setFloat64(7, 32.125);
+  Expect.equals(32.125, bytes.getFloat64(7));
+}
+
+main() {
+  for (var i = 0; i < 20; i++) {
+    unalignedFloat32();
+    unalignedFloat64();
+  }
+}