Fix issue 19424

editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/scope/LibraryImportScope.java

 /*
  * Copyright (c) 2012, 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
  * or implied. See the License for the specific language governing permissions and limitations under
  * the License.
  */
 package com.google.dart.engine.internal.scope;
 
 import com.google.dart.engine.AnalysisEngine;
+import com.google.dart.engine.ast.AstNode;
 import com.google.dart.engine.ast.Identifier;
 import com.google.dart.engine.element.Element;
 import com.google.dart.engine.element.ImportElement;
 import com.google.dart.engine.element.LibraryElement;
 import com.google.dart.engine.error.AnalysisError;
 import com.google.dart.engine.error.AnalysisErrorListener;
 import com.google.dart.engine.error.StaticWarningCode;
 import com.google.dart.engine.internal.element.MultiplyDefinedElementImpl;
+import com.google.dart.engine.source.Source;
 import com.google.dart.engine.utilities.general.StringUtilities;
 
 import java.util.ArrayList;
 import java.util.Arrays;
 
 /**
  * Instances of the class {@code LibraryImportScope} represent the scope containing all of the names
  * available from imported libraries.
  * 
  * @coverage dart.engine.resolver
@@ skipping 34 matching lines @@
       super.define(element);
     }
   }
 
   @Override
   public AnalysisErrorListener getErrorListener() {
     return errorListener;
   }
 
   @Override
+  protected Source getSource(AstNode node) {
+    Source source = super.getSource(node);
+    if (source == null) {
+      source = definingLibrary.getDefiningCompilationUnit().getSource();
+    }
+    return source;
+  }
+
+  @Override
   protected Element internalLookup(Identifier identifier, String name,
       LibraryElement referencingLibrary) {
     Element foundElement = localLookup(name, referencingLibrary);
     if (foundElement != null) {
       return foundElement;
     }
     for (int i = 0; i < importedNamespaces.length; i++) {
       Namespace nameSpace = importedNamespaces[i];
       Element element = nameSpace.get(name);
       if (element != null) {
@@ skipping 145 matching lines @@
       // All members were removed
       AnalysisEngine.getInstance().getLogger().logInformation(
           "Multiply defined SDK element: " + foundElement);
       return foundElement;
     }
     Element[] remaining = new Element[to];
     System.arraycopy(conflictingMembers, 0, remaining, 0, to);
     return new MultiplyDefinedElementImpl(definingLibrary.getContext(), remaining);
   }
 }