Fix more strong mode errors in analyzer

pkg/analyzer/lib/src/dart/element/handle.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 analyzer.src.generated.element_handle;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/constant/value.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
@@ skipping 77 matching lines @@
   @override
   InterfaceType get type => actualElement.type;
 
   @override
   List<TypeParameterElement> get typeParameters => actualElement.typeParameters;
 
   @override
   ConstructorElement get unnamedConstructor => actualElement.unnamedConstructor;
 
   @override
+  NamedCompilationUnitMember computeNode() => super.computeNode();
+
+  @override
   FieldElement getField(String fieldName) => actualElement.getField(fieldName);
 
   @override
   PropertyAccessorElement getGetter(String getterName) =>
       actualElement.getGetter(getterName);
 
   @override
   MethodElement getMethod(String methodName) =>
       actualElement.getMethod(methodName);
 
@@ skipping 780 matching lines @@
   ParameterKind get parameterKind => actualElement.parameterKind;
 
   @override
   List<ParameterElement> get parameters => actualElement.parameters;
 
   @override
   List<TypeParameterElement> get typeParameters => actualElement.typeParameters;
 
   @override
   SourceRange get visibleRange => actualElement.visibleRange;
+
+  @override
+  FormalParameter computeNode() => super.computeNode();
 }
 
 /**
  * A handle to a [PrefixElement].
  */
 class PrefixElementHandle extends ElementHandle implements PrefixElement {
   /**
    * Initialize a newly created element handle to represent the element at the
    * given [_location]. The [_resynthesizer] will be used to resynthesize the
    * element when needed.
@@ skipping 98 matching lines @@
    * Initialize a newly created element handle to represent the element at the
    * given [_location]. The [_resynthesizer] will be used to resynthesize the
    * element when needed.
    */
   TopLevelVariableElementHandle(
       ElementResynthesizer resynthesizer, ElementLocation location)
       : super(resynthesizer, location);
 
   @override
   ElementKind get kind => ElementKind.TOP_LEVEL_VARIABLE;
+
+  @override
+  VariableDeclaration computeNode() => super.computeNode();
 }
 
 /**
  * A handle to a [TypeParameterElement].
  */
 class TypeParameterElementHandle extends ElementHandle
     implements TypeParameterElement {
   /**
    * Initialize a newly created element handle to represent the element at the
    * given [_location]. The [_resynthesizer] will be used to resynthesize the
@@ skipping 42 matching lines @@
 
   @override
   FunctionElement get initializer => actualElement.initializer;
 
   @override
   bool get isConst => actualElement.isConst;
 
   @override
   bool get isFinal => actualElement.isFinal;
 
+  @deprecated
   @override
   bool get isPotentiallyMutatedInClosure =>
       actualElement.isPotentiallyMutatedInClosure;
 
+  @deprecated
   @override
   bool get isPotentiallyMutatedInScope =>
       actualElement.isPotentiallyMutatedInScope;
 
   @override
   bool get isStatic => actualElement.isStatic;
 
   @override
   DartType get type => actualElement.type;
 }