Refactor Parsing to remove compiler dependency

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 198 matching lines @@
           assert(listener.nodes.isEmpty);
         }));
   }
 }
 
 class PatchMemberListener extends MemberListener {
   final Compiler compiler;
 
   PatchMemberListener(Compiler compiler, ClassElement enclosingClass)
       : this.compiler = compiler,
-        super(compiler.parsing.getScannerOptionsFor(enclosingClass),
+        super(compiler.parsingContext.getScannerOptionsFor(enclosingClass),
             compiler.reporter, enclosingClass);
 
   @override
   void addMember(Element patch) {
     addMetadata(patch);
 
     PatchVersion patchVersion = getPatchVersion(compiler, patch);
     if (patchVersion != null) {
       if (patchVersion.isActive(compiler.patchVersion)) {
         Element origin = enclosingClass.origin.localLookup(patch.name);
@@ skipping 24 matching lines @@
 
 /**
  * Extension of [ElementListener] for parsing patch files.
  */
 class PatchElementListener extends ElementListener implements Listener {
   final Compiler compiler;
 
   PatchElementListener(Compiler compiler, CompilationUnitElement patchElement,
       IdGenerator idGenerator)
       : this.compiler = compiler,
-        super(compiler.parsing.getScannerOptionsFor(patchElement),
+        super(compiler.parsingContext.getScannerOptionsFor(patchElement),
             compiler.reporter, patchElement, idGenerator);
 
   @override
   void pushElement(Element patch) {
     popMetadata(patch);
 
     PatchVersion patchVersion = getPatchVersion(compiler, patch);
     if (patchVersion != null) {
       if (patchVersion.isActive(compiler.patchVersion)) {
         LibraryElement originLibrary = compilationUnitElement.library;
@@ skipping 336 matching lines @@
 
 class PatchVersion {
   final String tag;
 
   const PatchVersion(this.tag);
 
   bool isActive(String patchTag) => tag == null || tag == patchTag;
 
   String toString() => 'PatchVersion($tag)';
 }