Show import for import of parts.

pkg/compiler/lib/src/library_loader.dart

 // 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.
 
 library dart2js.library_loader;
 
 import 'dart:async';
 
 import 'common.dart';
 import 'common/names.dart' show
@@ skipping 592 matching lines @@
     var readScript = compiler.readScript;
     if (readableUri == null) {
       readableUri = resolvedUri;
       readScript = compiler.synthesizeScript;
     }
     return reporter.withCurrentElement(importingLibrary, () {
       return readScript(node, readableUri).then((Script script) {
         if (script == null) return null;
         LibraryElement element =
             createLibrarySync(handler, script, resolvedUri);
+        CompilationUnitElementX compilationUnit = element.entryCompilationUnit;
+        if (compilationUnit.partTag != null) {
+          DiagnosticMessage error = reporter.withCurrentElement(
+              compilationUnit,
+              () => reporter.createMessage(
+                  compilationUnit.partTag, MessageKind.IMPORT_PART_OF));
+          DiagnosticMessage info = reporter.withCurrentElement(
+              importingLibrary,
+              () => reporter.createMessage(
+                  node,
+                  MessageKind.IMPORT_PART_OF_HERE));
+          reporter.reportError(error, <DiagnosticMessage>[info]);
+        }
         return processLibraryTags(handler, element).then((_) {
           reporter.withCurrentElement(element, () {
             handler.registerLibraryExports(element);
           });
           return element;
         });
       });
     });
   }
 
@@ skipping 719 matching lines @@
         }
         suffixes.add(const Link<Uri>().prepend(canonicalUri));
       }
       suffixChainMap[library] = suffixes;
       return;
     }
 
     computeSuffixes(rootLibrary, const Link<Uri>());
   }
 }