fixes #52, fields shadowing getters/setters or other fields

lib/runtime/dart/typed_data.js

 var typed_data;
 (function(exports) {
   'use strict';
   class ByteBuffer extends core.Object {}
   class TypedData extends core.Object {}
   let _ = Symbol('_');
   let _littleEndian = Symbol('_littleEndian');
   class Endianness extends core.Object {
     [_](littleEndian) {
-      this[_littleEndian] = littleEndian;
+      dart.initField(Endianness, this, _littleEndian, littleEndian);
     }
   }
   dart.defineNamedConstructor(Endianness, _);
   Endianness.BIG_ENDIAN = new Endianness[_](false);
   Endianness.LITTLE_ENDIAN = new Endianness[_](true);
   dart.defineLazyProperties(Endianness, {
     get HOST_ENDIAN() {
       return new ByteData.view(new Uint16List.fromList(dart.as(new core.List.from([1]), core.List$(core.int))).buffer).getInt8(0) == 1 ? Endianness.LITTLE_ENDIAN : Endianness.BIG_ENDIAN;
     }
   });
@@ skipping 856 matching lines @@
   exports.Uint64List = Uint64List;
   exports.Float32List = Float32List;
   exports.Float64List = Float64List;
   exports.Float32x4List = Float32x4List;
   exports.Int32x4List = Int32x4List;
   exports.Float64x2List = Float64x2List;
   exports.Float32x4 = Float32x4;
   exports.Int32x4 = Int32x4;
   exports.Float64x2 = Float64x2;
 })(typed_data || (typed_data = {}));