Move dart2js from sdk/lib/_internal/compiler to pkg/compiler

pkg/compiler/lib/src/patch_parser.dart

 // Copyright (c) 2012, 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 contains the infrastructure to parse and integrate patch files.
  *
  * Three types of elements can be patched: [LibraryElement], [ClassElement],
  * [FunctionElement]. Patches are introduced in patch libraries which are loaded
  * together with the corresponding origin library. Which libraries that are
@@ skipping 493 matching lines @@
         "Trying to patch a function more than once.");
   }
   origin.applyPatch(patch);
 }
 
 // TODO(johnniwinther): Add unittest when patch is (real) metadata.
 bool isPatchElement(Compiler compiler, Element element) {
   return EagerAnnotationHandler.checkAnnotation(compiler, element,
       const PatchAnnotationHandler());
 }