Add an option for incremental resolution of API breaking changes.

pkg/analyzer/lib/src/generated/incremental_resolver.dart

 // Copyright (c) 2014, 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.
 
 library engine.incremental_resolver;
 
 import 'dart:collection';
 import 'dart:math' as math;
 
 import 'ast.dart';
 import 'element.dart';
 import 'engine.dart';
 import 'error.dart';
 import 'error_verifier.dart';
 import 'incremental_logger.dart' show logger, LoggingTimer;
 import 'java_engine.dart';
 import 'parser.dart';
 import 'resolver.dart';
 import 'scanner.dart';
 import 'source.dart';
 import 'utilities_dart.dart';
 
 
 /**
+ * If `true`, an attempt to resolve API-changing modifications is made.
+ */
+bool _resolveApiChanges = false;
+
+
+/**
  * Instances of the class [DeclarationMatcher] determine whether the element
  * model defined by a given AST structure matches an existing element model.
  */
 class DeclarationMatcher extends RecursiveAstVisitor {
   /**
    * The libary containing the AST nodes being visited.
    */
   LibraryElement _enclosingLibrary;
 
   /**
@@ skipping 914 matching lines @@
   int _updateEndOld;
   int _updateEndNew;
 
   List<AnalysisError> _newScanErrors = <AnalysisError>[];
   List<AnalysisError> _newParseErrors = <AnalysisError>[];
   List<AnalysisError> _newResolveErrors = <AnalysisError>[];
   List<AnalysisError> _newVerifyErrors = <AnalysisError>[];
   List<AnalysisError> _newHints = <AnalysisError>[];
 
   PoorMansIncrementalResolver(this._typeProvider, this._unitSource,
-      this._librarySource, this._entry);
+      this._librarySource, this._entry, bool resolveApiChanges) {
+    _resolveApiChanges = resolveApiChanges;
+  }
 
   /**
    * Attempts to update [oldUnit] to the state corresponding to [newCode].
    * Returns `true` if success, or `false` otherwise.
    * The [oldUnit] might be damaged.
    */
   bool resolve(CompilationUnit oldUnit, String newCode) {
     logger.enter('diff/resolve $_unitSource');
     logger.log(oldUnit != null ? 'has oldUnit' : 'oldUnit is null');
     try {
@@ skipping 686 matching lines @@
   String toString() => name;
 }
 
 
 class _TokenPair {
   final _TokenDifferenceKind kind;
   final Token oldToken;
   final Token newToken;
   _TokenPair(this.kind, this.oldToken, this.newToken);
 }