Move runtime js files down to lib/runtime/dart

lib/runtime/_errors.js

-// 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.
-
-/*
- * This library encapsulates the core sdk errors that the runtime knows about.
- *
- */
-
-dart_library.library('dart_runtime/_errors', null, /* Imports */[
-], /* Lazy Imports */[
-  'dart_runtime/_operations',
-  'dart/core',
-  'dart/_js_helper'
-], function(exports, operations, core, _js_helper) {
-  'use strict';
-
-  function throwNoSuchMethod(obj, name, pArgs, nArgs, extras) {
-    operations.throw(new core.NoSuchMethodError(obj, name, pArgs, nArgs, extras));
-  }
-  exports.throwNoSuchMethod = throwNoSuchMethod;
-
-  function throwCastError(actual, type) {
-    operations.throw(new _js_helper.CastErrorImplementation(actual, type));
-  }
-  exports.throwCastError = throwCastError;
-
-  function throwAssertionError() {
-    operations.throw(new core.AssertionError());
-  }
-  exports.throwAssertionError = throwAssertionError;
-
-  function throwNullValueError() {
-    // 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.
-    operations.throw(new core.NoSuchMethodError(null,
-      new core.Symbol('<Unexpected Null Value>'), null, null, null));
-  }
-  exports.throwNullValueError = throwNullValueError;
-});