fix for dartbug.com/9512 - don't show errors in packages

editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/internal/builder/AnalysisWorker.java

 /*
  * Copyright (c) 2013, the Dart project authors.
  * 
  * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
  * 
  * http://www.eclipse.org/legal/epl-v10.html
  * 
  * Unless required by applicable law or agreed to in writing, software distributed under the License
  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
@@ skipping 107 matching lines @@
 
     // If errors are available, then queue the errors to be translated to markers
     AnalysisError[] errors = change.getErrors();
     if (errors != null) {
       Source source = change.getSource();
       IResource res = project.getResource(source);
       if (res == null) {
         // TODO (danrubel): log unmatched sources once context only returns errors for added sources
 //        DartCore.logError("Failed to determine resource for: " + source);
       } else {
-        LineInfo lineInfo = change.getLineInfo();
-        if (lineInfo == null) {
-          DartCore.logError("Missing line information for: " + source);
-        } else {
-          markerManager.queueErrors(res, lineInfo, errors);
+        if (!DartCore.isContainedInPackages(res.getLocation().toFile())) {
+          LineInfo lineInfo = change.getLineInfo();
+          if (lineInfo == null) {
+            DartCore.logError("Missing line information for: " + source);
+          } else {
+            markerManager.queueErrors(res, lineInfo, errors);
+          }
         }
       }
     }
 
     // If there is a unit to be indexed, then do so
     CompilationUnit unit = change.getCompilationUnit();
     if (unit != null) {
       index.indexUnit(context, unit);
     }
   }
@@ skipping 11 matching lines @@
       return false;
     }
 
     // process results and return true indicating there might be more analysis
     for (ChangeNotice change : changes) {
       processChange(change);
     }
     return true;
   }
 }