Support for same prefix for multiple imports.

compiler/java/com/google/dart/compiler/resolver/ResolutionContext.java

 // Copyright (c) 2012, 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.
 
 package com.google.dart.compiler.resolver;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.dart.compiler.DartCompilationError;
 import com.google.dart.compiler.DartCompilerContext;
 import com.google.dart.compiler.ErrorCode;
 import com.google.dart.compiler.ErrorSeverity;
@@ skipping 367 matching lines @@
     @Override
     public Element visitNode(DartNode node) {
       throw internalError(node, "Unexpected node: %s", node);
     }
 
     @Override
     public Element visitPropertyAccess(DartPropertyAccess node) {
       Element element = node.getQualifier().accept(this);
       if (element != null) {
         switch (element.getKind()) {
-          case LIBRARY :
-            Scope elementScope = ((LibraryElement) element).getScope();
+          case LIBRARY_PREFIX :
+            Scope elementScope = ((LibraryPrefixElement) element).getScope();
             return elementScope.findElement(scope.getLibrary(), node.getPropertyName());
           case CLASS :
             return Elements.findElement((ClassElement) element, node.getPropertyName());
         }
       }
       return null;
     }
 
     @Override
     public Element visitIdentifier(DartIdentifier node) {
       String name = node.getName();
       return scope.findElement(scope.getLibrary(), name);
     }
 
     @Override
     public Element visitSyntheticErrorIdentifier(DartSyntheticErrorIdentifier node) {
       return Elements.dynamicElement();
     }
   }
 }