Fix summarization of closures in toplevel variable declarations in part files.

pkg/analyzer/lib/src/summary/link.dart

 // Copyright (c) 2016, 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.
 
 /**
  * This library is capable of producing linked summaries from unlinked
  * ones (or prelinked ones).  It functions by building a miniature
  * element model to represent the contents of the summaries, and then
  * scanning the element model to gather linked information and adding
  * it to the summary data structures.
@@ skipping 1198 matching lines @@
               ? ReferenceKind.method
               : ReferenceKind.topLevelFunction;
           break;
         case UnlinkedExecutableKind.setter:
           kind = ReferenceKind.propertyAccessor;
           break;
         default:
           // TODO(paulberry): implement other cases as necessary
           throw new UnimplementedError('${element._unlinkedExecutable.kind}');
       }
-      return addRawReference(element.name,
-          numTypeParameters: element.typeParameters.length,
-          containingReference:
-              enclosingClass != null ? addReference(enclosingClass) : null,
-          dependency: enclosingClass != null
-              ? null
-              : library.addDependency(element.library as LibraryElementForLink),
-          kind: kind);
+      if (enclosingClass == null) {
+        return addRawReference(element.name,
+            numTypeParameters: element.typeParameters.length,
+            dependency:
+                library.addDependency(element.library as LibraryElementForLink),
+            unitNum: element.compilationUnit.unitNum,
+            kind: kind);
+      } else {
+        return addRawReference(element.name,
+            numTypeParameters: element.typeParameters.length,
+            containingReference: addReference(enclosingClass),
+            kind: kind);
+      }
     } else if (element is FunctionElementForLink_Initializer) {
       return addRawReference('',
           containingReference: addReference(element.enclosingElement),
           kind: ReferenceKind.function);
     } else if (element is TopLevelVariableElementForLink) {
       return addRawReference(element.name,
           dependency: library.addDependency(element.library),
+          unitNum: element.compilationUnit.unitNum,
           kind: ReferenceKind.topLevelPropertyAccessor);
     } else if (element is FieldElementForLink_ClassField) {
       ClassElementForLink_Class enclosingClass = element.enclosingElement;
       // Note: even if the class has type parameters, we don't need to set
       // numTypeParameters because numTypeParameters does not count type
       // parameters of parent elements (see
       // [LinkedReference.numTypeParameters]).
       return addRawReference(element.name,
           containingReference: addReference(enclosingClass),
           kind: ReferenceKind.propertyAccessor);
@@ skipping 3809 matching lines @@
    * there are no type parameters in scope.
    */
   TypeParameterizedElementMixin get _typeParameterContext;
 
   @override
   noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 
   @override
   String toString() => '$enclosingElement.$name';
 }