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

Index: editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/internal/builder/AnalysisWorker.java
===================================================================
--- editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/internal/builder/AnalysisWorker.java	(revision 20660)
+++ editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/internal/builder/AnalysisWorker.java	(working copy)
@@ -125,11 +125,13 @@
         // 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);
+          }
         }
       }
     }