Remove CompilationUnitElement.getElementAt().

pkg/analyzer/lib/src/fasta/mock_element.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.mock_element;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 
@@ skipping 199 matching lines @@
 
   @override
   LineInfo get lineInfo => internalError("not supported.");
 
   List<TopLevelVariableElement> get topLevelVariables {
     return internalError("not supported.");
   }
 
   List<ClassElement> get types => internalError("not supported.");
 
-  Element getElementAt(int offset) => internalError("not supported.");
-
   ClassElement getEnum(String name) => internalError("not supported.");
 
   ClassElement getType(String name) => internalError("not supported.");
 
   CompilationUnit computeNode() => internalError("not supported.");
 }
 
 abstract class MockClassElement extends MockElement implements ClassElement {
   MockClassElement() : super(ElementKind.CLASS);
 
@@ skipping 147 matching lines @@
   get constantValue => internalError("not supported.");
 
   computeConstantValue() => internalError("not supported.");
 
   void appendToWithoutDelimiters(StringBuffer buffer) {
     return internalError("not supported.");
   }
 
   FormalParameter computeNode() => internalError("not supported.");
 }