Partial fix for AST cloning

pkg/analyzer/lib/src/analyzer_impl.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.
 
 library analyzer_impl;
 
 import 'dart:async';
 
 import 'dart:io';
 
 import 'package:path/path.dart' as pathos;
 
-import 'generated/ast.dart';
 import 'generated/engine.dart';
 import 'generated/element.dart';
 import 'generated/error.dart';
 import 'generated/java_io.dart';
 import 'generated/sdk.dart';
 import 'generated/sdk_io.dart';
 import 'generated/source_io.dart';
 import '../options.dart';
 
 import 'dart:collection';
@@ skipping 64 matching lines @@
     JavaFile sourceFile = new JavaFile(sourcePath);
     UriKind uriKind = getUriKind(sourceFile);
     librarySource = new FileBasedSource.con2(sourceFile, uriKind);
 
     // prepare context
     prepareAnalysisContext(sourceFile, librarySource);
   }
 
   /// The sync version of analysis
   ErrorSeverity _analyzeSync() {
-    // don't try to analyzer parts
-    var unit = context.parseCompilationUnit(librarySource);
-    var hasLibraryDirective = false;
-    var hasPartOfDirective = false;
-    for (var directive in unit.directives) {
-      if (directive is LibraryDirective) hasLibraryDirective = true;
-      if (directive is PartOfDirective) hasPartOfDirective = true;
-    }
-    if (hasPartOfDirective && !hasLibraryDirective) {
+    // don't try to analyze parts
+    if (context.getKindOf(librarySource) == SourceKind.PART) {
       print("Only libraries can be analyzed.");
       print("$sourcePath is a part and can not be analyzed.");
       return ErrorSeverity.ERROR;
     }
     // resolve library
     var libraryElement = context.computeLibraryElement(librarySource);
     // prepare source and errors
     prepareSources(libraryElement);
     prepareErrors();
 
@@ skipping 247 matching lines @@
     }
   }
 
   @override
   void logInformation2(String message, Exception exception) {
     if (log) {
       stdout.writeln(message);
     }
   }
 }