[arm, arm64] Implemented unaligned scalar float access.

tests/language/vm/unaligned_float_access_register_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);
   for (var i = 0; i < 4; i++) {
-    bytes.setFloat32(i, 16.25);
-    Expect.equals(16.25, bytes.getFloat32(i));
+    bytes.setFloat32(i, 16.25, Endianness.HOST_ENDIAN);
+    Expect.equals(16.25, bytes.getFloat32(i, Endianness.HOST_ENDIAN));
   }
 }
 
 unalignedFloat64() {
   var bytes = new ByteData(64);
   for (var i = 0; i < 8; i++) {
-    bytes.setFloat64(i, 16.25);
-    Expect.equals(16.25, bytes.getFloat64(i));
+    bytes.setFloat64(i, 16.25, Endianness.HOST_ENDIAN);
+    Expect.equals(16.25, bytes.getFloat64(i, Endianness.HOST_ENDIAN));
   }
 }
 
 main() {
   for (var i = 0; i < 20; i++) {
     unalignedFloat32();
     unalignedFloat64();
   }
 }