Reorganize tool/input_sdk/private

tool/input_sdk/private/ddc_runtime/errors.dart

 // Copyright (c) 2015, 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.
 part of dart._runtime;
 
 throwCastError(actual, type) => JS('', '''(() => {
   $throw_(new $CastErrorImplementation($actual, $type));
 })()''');
 
 throwAssertionError() => JS('', '''(() => {
   $throw_(new $AssertionError());
 })()''');
 
 throwNullValueError() => JS('', '''(() => {
   // TODO(vsm): Per spec, we should throw an NSM here.  Technically, we ought
   // to thread through method info, but that uglifies the code and can't
   // actually be queried ... it only affects how the error is printed.
   $throw_(new $NoSuchMethodError(null,
       new $Symbol('<Unexpected Null Value>'), null, null, null));
 })()''');