sdk files reorganization to make dart2js a proper package

sdk/lib/_internal/compiler/js_lib/internal_patch.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.
-
-import 'dart:_js_primitives' show printString;
-import 'dart:_js_helper' show JS, patch;
-import 'dart:_interceptors' show JSArray;
-
-@patch
-class Symbol implements core.Symbol {
-  @patch
-  const Symbol(String name)
-      : this._name = name;
-}
-
-@patch
-void printToConsole(String line) {
-  printString('$line');
-}
-
-@patch
-List makeListFixedLength(List growableList) {
-  return JSArray.markFixedList(growableList);
-}
-
-@patch
-List makeFixedListUnmodifiable(List fixedLengthList) {
-  return JSArray.markUnmodifiableList(fixedLengthList);
-}