Fix coded buffer reader so all tests pass using dart2js.

test/codec_test.dart

 #!/usr/bin/env 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.
 
-@TestOn("dart-vm")
 library pb_codec_tests;
 
 import 'dart:typed_data';
 
 import 'package:protobuf/protobuf.dart';
 import 'package:test/test.dart';
 
 import 'test_util.dart';
 
 void main() {
@@ skipping 162 matching lines @@
     readFloat(int bits) {
       var bytes = dataToBytes(
           new ByteData(4)..setUint32(0, bits, Endianness.LITTLE_ENDIAN));
       return new CodedBufferReader(bytes).readFloat();
     }
 
     expect(floatToBits(value), bits);
     expect(readFloat(bits), doubleEquals(value));
   }
 
+  final doubleToBytes = convertToBytes(PbFieldType.OD);
+
   void _test64(List<int> hilo, double value) {
-    readDouble(int bits) {
-      var bytes = dataToBytes(
-          new ByteData(8)..setUint64(0, bits, Endianness.LITTLE_ENDIAN));
-      return new CodedBufferReader(bytes).readDouble();
-    }
+    // Encode a double to its wire format.
+    ByteData data = makeData(doubleToBytes(value));
+    var actualHilo = [
+      data.getUint32(4, Endianness.LITTLE_ENDIAN),
+      data.getUint32(0, Endianness.LITTLE_ENDIAN)
+    ];
+    //int encoded = data.getUint64(0, Endianness.LITTLE_ENDIAN);
+    expect(actualHilo, hilo);
 
-    final doubleToBytes = convertToBytes(PbFieldType.OD);
-    doubleToBits(double value) =>
-        makeData(doubleToBytes(value)).getUint64(0, Endianness.LITTLE_ENDIAN);
-
-    int bits = (hilo[0] << 32) | hilo[1];
-    expect(doubleToBits(value), bits);
-    expect(readDouble(bits), doubleEquals(value));
+    // Decode it again (round trip).
+    List<int> bytes = dataToBytes(data);
+    double reencoded = new CodedBufferReader(bytes).readDouble();
+    expect(reencoded, doubleEquals(value));
   }
 
   test('testFloat', () {
     // Denorms.
     _test32(0x1, 1.401298464324817E-45);
     _test32(0x2, 1.401298464324817E-45 * 2.0);
     _test32(0x3, 1.401298464324817E-45 * 3.0);
     _test32(0x00ba98, 1.401298464324817E-45 * 0x00ba98);
     _test32(8034422, 1.401298464324817E-45 * 8034422);
     _test32(0x7fffff, 1.401298464324817E-45 * 0x7fffff);
@@ skipping 531 matching lines @@
     expect(readUint64([0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f]),
         expect64(0xffffffff, 0xffffff));
     expect(
         readUint64(
             [0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x01]),
         expect64(0xffffffff, 0xffffffff));
     expect(readUint64([180, 222, 252, 255, 255, 255, 255, 255, 255, 1]),
         expect64(0xffff2f34, 0xffffffff));
   });
 }