Issue 21373. Fix for removing line info in case of exception (causes NPE in outline computer).

pkg/analysis_server/lib/src/computer/computer_outline.dart

 // Copyright (c) 2014, 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 computer.outline;
 
 import 'package:analysis_server/src/collections.dart';
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart' as engine;
-import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/source.dart';
 
 
 /**
  * A computer for [CompilationUnit] outline.
  */
 class DartUnitOutlineComputer {
-  final CompilationUnit _unit;
-  String file;
-  LineInfo lineInfo;
+  final String file;
+  final CompilationUnit unit;
+  final LineInfo lineInfo;
 
-  DartUnitOutlineComputer(AnalysisContext context, Source source, this._unit) {
-    file = source.fullName;
-    lineInfo = context.getLineInfo(source);
-  }
+  DartUnitOutlineComputer(Source source, this.lineInfo, this.unit)
+      : file = source.fullName;
 
   /**
    * Returns the computed outline, not `null`.
    */
   Outline compute() {
     List<Outline> unitContents = <Outline>[];
-    for (CompilationUnitMember unitMember in _unit.declarations) {
+    for (CompilationUnitMember unitMember in unit.declarations) {
       if (unitMember is ClassDeclaration) {
         ClassDeclaration classDeclaration = unitMember;
         List<Outline> classContents = <Outline>[];
         for (ClassMember classMember in classDeclaration.members) {
           if (classMember is ConstructorDeclaration) {
             ConstructorDeclaration constructorDeclaration = classMember;
             classContents.add(_newConstructorOutline(constructorDeclaration));
           }
           if (classMember is FieldDeclaration) {
             FieldDeclaration fieldDeclaration = classMember;
@@ skipping 277 matching lines @@
         sourceRegion.length,
         children: nullIfEmpty(contents));
     return outline;
   }
 
   Outline _newUnitOutline(List<Outline> unitContents) {
     Element element = new Element(
         ElementKind.COMPILATION_UNIT,
         '<unit>',
         Element.makeFlags(),
-        location: _getLocationNode(_unit));
+        location: _getLocationNode(unit));
     return new Outline(
         element,
-        _unit.offset,
-        _unit.length,
+        unit.offset,
+        unit.length,
         children: nullIfEmpty(unitContents));
   }
 
   Outline _newVariableOutline(String typeName, ElementKind kind,
       VariableDeclaration variable, bool isStatic) {
     SimpleIdentifier nameNode = variable.name;
     String name = nameNode.name;
     _SourceRegion sourceRegion = _getSourceRegion(variable);
     Element element = new Element(
         kind,
@@ skipping 38 matching lines @@
 
 
 /**
  * A range of characters.
  */
 class _SourceRegion {
   final int length;
   final int offset;
   _SourceRegion(this.offset, this.length);
 }