Ensure locations are always provided, but don't store them yet.

pkg/front_end/lib/src/fasta/analyzer/element_store.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.
 
 library fasta.analyzer.element_store;
 
 import 'package:kernel/analyzer/loader.dart' show
     ReferenceLevelLoader;
 
 import 'package:kernel/ast.dart';
@@ skipping 226 matching lines @@
 class KernelParameterElement extends MockParameterElement {
   final VariableDeclaration declaration;
 
   final ParameterKind parameterKind;
 
   KernelParameterElement(this.declaration, this.parameterKind);
 }
 
 /// Both an [Element] and [Builder] to using memory to store local elements in
 /// [ElementStore].
-class AnalyzerLocalVariableElemment extends MockElement with Builder
+class AnalyzerLocalVariableElemment extends MockElement
     implements LocalVariableElement {
   final analyzer.VariableDeclaration variable;
 
   AnalyzerLocalVariableElemment(this.variable)
       : super(ElementKind.LOCAL_VARIABLE);
 
   String get name => variable.name.name;
 
   bool get isFinal => false; // TODO(ahe): implement this.
 
   bool get isConst => false; // TODO(ahe): implement this.
 
   analyzer.VariableDeclaration get target => variable;
 }
 
 /// Both an [Element] and [Builder] to using memory to store local elements in
 /// [ElementStore].
-class AnalyzerParameterElement extends MockParameterElement with Builder {
+class AnalyzerParameterElement extends MockParameterElement {
   final analyzer.FormalParameter parameter;
 
   AnalyzerParameterElement(this.parameter);
 
   String get name => parameter.identifier.name;
 
   bool get isFinal => false; // TODO(ahe): implement this.
 
   bool get isConst => false; // TODO(ahe): implement this.
 
@@ skipping 10 matching lines @@
   }
 }
 
 class KernelInterfaceType extends MockInterfaceType {
   final KernelClassElement element;
 
   KernelInterfaceType(this.element);
 
   List<analyzer.DartType> get typeArguments => const <analyzer.DartType>[];
 }