Don't index library identifiers.

pkg/analyzer/lib/src/summary/index_unit.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.
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/member.dart';
@@ skipping 486 matching lines @@
   visitIndexExpression(IndexExpression node) {
     MethodElement element = node.bestElement;
     if (element is MethodElement) {
       Token operator = node.leftBracket;
       recordRelationToken(element, IndexRelationKind.IS_INVOKED_BY, operator);
     }
     super.visitIndexExpression(node);
   }
 
   @override
+  visitLibraryIdentifier(LibraryIdentifier node) {}
+
+  @override
   visitMethodInvocation(MethodInvocation node) {
     SimpleIdentifier name = node.methodName;
     Element element = name.bestElement;
     // unresolved name invocation
     bool isQualified = node.realTarget != null;
     if (element == null) {
       recordNameRelation(name, IndexRelationKind.IS_INVOKED_BY, isQualified);
     }
     // element invocation
     IndexRelationKind kind = element is ClassElement
@@ skipping 280 matching lines @@
         usedNameOffsets: nameRelations.map((r) => r.offset).toList(),
         usedNameIsQualifiedFlags:
             nameRelations.map((r) => r.isQualified).toList());
   }
 
   void defineName(String name, IndexNameKind kind, int offset) {
     _StringInfo nameInfo = pkg._getStringInfo(name);
     definedNames.add(new _DefinedNameInfo(nameInfo, kind, offset));
   }
 }