Add line starts into unlinked units.

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

 // Copyright (c) 2015, 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 serialization.elements;
 
 import 'dart:convert';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/member.dart';
 import 'package:analyzer/src/dart/element/type.dart';
+import 'package:analyzer/src/generated/java_engine.dart';
 import 'package:analyzer/src/generated/resolver.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/utilities_dart.dart';
 import 'package:analyzer/src/summary/api_signature.dart';
 import 'package:analyzer/src/summary/format.dart';
 import 'package:analyzer/src/summary/idl.dart';
 import 'package:analyzer/src/summary/name_filter.dart';
 import 'package:analyzer/src/summary/summarize_const_expr.dart';
 import 'package:convert/convert.dart';
 import 'package:crypto/crypto.dart';
@@ skipping 418 matching lines @@
       if (accessor.isSynthetic && accessor.isGetter) {
         PropertyInducingElement variable = accessor.variable;
         if (variable != null) {
           assert(!variable.isSynthetic);
           variables.add(serializeVariable(variable));
         }
       }
     }
     unlinkedUnit.variables = variables;
     unlinkedUnit.references = unlinkedReferences;
+    unlinkedUnit.lineStarts =
+        compilationUnit.context?.computeLineInfo(unitSource)?.lineStarts ??

[Paul Berry, 2016/08/08 18:38:10]

Nit: the `?? const <int>[]` isn't necessary.  The default value of the field
(which is the empty list) should automatically be used if you try to assign
`null`.

+            const <int>[];
     linkedUnit.references = linkedReferences;
     unitUri = compilationUnit.source.uri.toString();
   }
 
   /**
    * Create the [LinkedUnit.types] table based on deferred types that were
    * found during [addCompilationUnitElements].  Also populate
    * [LinkedUnit.constCycles].
    */
   void createLinkedInfo() {
@@ skipping 1217 matching lines @@
       exportNames.add(new LinkedExportNameBuilder(
           name: name,
           dependency: serializeDependency(dependentLibrary),
           unit: unit,
           kind: kind));
     }
     pb.exportNames = exportNames;
     return pb;
   }
 }