Use null-aware operators to clean up the code

pkg/analyzer/lib/src/dart/ast/ast.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.dart.ast.ast;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 1752 matching lines @@
     ..add(_typeParameters)
     ..add(_extendsClause)
     ..add(_withClause)
     ..add(_implementsClause)
     ..add(_nativeClause)
     ..add(leftBracket)
     ..addAll(members)
     ..add(rightBracket);
 
   @override
-  ClassElement get element =>
-      _name != null ? (_name.staticElement as ClassElement) : null;
+  ClassElement get element => _name?.staticElement as ClassElement;
 
   @override
   Token get endToken => rightBracket;
 
   @override
   ExtendsClause get extendsClause => _extendsClause;
 
   @override
   void set extendsClause(ExtendsClause extendsClause) {
     _extendsClause = _becomeParentOf(extendsClause);
@@ skipping 202 matching lines @@
     ..add(_name)
     ..add(_typeParameters)
     ..add(equals)
     ..add(abstractKeyword)
     ..add(_superclass)
     ..add(_withClause)
     ..add(_implementsClause)
     ..add(semicolon);
 
   @override
-  ClassElement get element =>
-      _name != null ? (_name.staticElement as ClassElement) : null;
+  ClassElement get element => _name?.staticElement as ClassElement;
 
   @override
   Token get firstTokenAfterCommentAndMetadata {
     if (abstractKeyword != null) {
       return abstractKeyword;
     }
     return typedefKeyword;
   }
 
   @override
@@ skipping 1683 matching lines @@
   EnumConstantDeclarationImpl(
       Comment comment, List<Annotation> metadata, SimpleIdentifier name)
       : super(comment, metadata) {
     _name = _becomeParentOf(name);
   }
 
   @override
   Iterable get childEntities => super._childEntities..add(_name);
 
   @override
-  FieldElement get element =>
-      _name == null ? null : (_name.staticElement as FieldElement);
+  FieldElement get element => _name?.staticElement as FieldElement;
 
   @override
   Token get endToken => _name.endToken;
 
   @override
   Token get firstTokenAfterCommentAndMetadata => _name.beginToken;
 
   @override
   SimpleIdentifier get name => _name;
 
@@ skipping 68 matching lines @@
     ..add(enumKeyword)
     ..add(_name)
     ..add(leftBracket)
     ..addAll(_constants)
     ..add(rightBracket);
 
   @override
   NodeList<EnumConstantDeclaration> get constants => _constants;
 
   @override
-  ClassElement get element =>
-      _name != null ? (_name.staticElement as ClassElement) : null;
+  ClassElement get element => _name?.staticElement as ClassElement;
 
   @override
   Token get endToken => rightBracket;
 
   @override
   Token get firstTokenAfterCommentAndMetadata => enumKeyword;
 
   @override
   dynamic/*=E*/ accept/*<E>*/(AstVisitor/*<E>*/ visitor) =>
       visitor.visitEnumDeclaration(this);
@@ skipping 1188 matching lines @@
 
   @override
   Iterable get childEntities => super._childEntities
     ..add(externalKeyword)
     ..add(_returnType)
     ..add(propertyKeyword)
     ..add(_name)
     ..add(_functionExpression);
 
   @override
-  ExecutableElement get element =>
-      _name != null ? (_name.staticElement as ExecutableElement) : null;
+  ExecutableElement get element => _name?.staticElement as ExecutableElement;
 
   @override
   Token get endToken => _functionExpression.endToken;
 
   @override
   Token get firstTokenAfterCommentAndMetadata {
     if (externalKeyword != null) {
       return externalKeyword;
     } else if (_returnType != null) {
       return _returnType.beginToken;
@@ skipping 330 matching lines @@
   Iterable get childEntities => super._childEntities
     ..add(typedefKeyword)
     ..add(_returnType)
     ..add(_name)
     ..add(_typeParameters)
     ..add(_parameters)
     ..add(semicolon);
 
   @override
   FunctionTypeAliasElement get element =>
-      _name != null ? (_name.staticElement as FunctionTypeAliasElement) : null;
+      _name?.staticElement as FunctionTypeAliasElement;
 
   @override
   FormalParameterList get parameters => _parameters;
 
   @override
   void set parameters(FormalParameterList parameters) {
     _parameters = _becomeParentOf(parameters);
   }
 
   @override
@@ skipping 1708 matching lines @@
     ..add(_body);
 
   /**
    * Return the element associated with this method, or `null` if the AST
    * structure has not been resolved. The element can either be a
    * [MethodElement], if this represents the declaration of a normal method, or
    * a [PropertyAccessorElement] if this represents the declaration of either a
    * getter or a setter.
    */
   @override
-  ExecutableElement get element =>
-      _name != null ? (_name.staticElement as ExecutableElement) : null;
+  ExecutableElement get element => _name?.staticElement as ExecutableElement;
 
   @override
   Token get endToken => _body.endToken;
 
   @override
   Token get firstTokenAfterCommentAndMetadata {
     if (externalKeyword != null) {
       return externalKeyword;
     } else if (modifierKeyword != null) {
       return modifierKeyword;
@@ skipping 3233 matching lines @@
   void set bound(TypeName typeName) {
     _bound = _becomeParentOf(typeName);
   }
 
   @override
   Iterable get childEntities =>
       super._childEntities..add(_name)..add(extendsKeyword)..add(_bound);
 
   @override
   TypeParameterElement get element =>
-      _name != null ? (_name.staticElement as TypeParameterElement) : null;
+      _name?.staticElement as TypeParameterElement;
 
   @override
   Token get endToken {
     if (_bound == null) {
       return _name.endToken;
     }
     return _bound.endToken;
   }
 
   @override
@@ skipping 236 matching lines @@
     if (comment == null) {
       AstNode node = parent?.parent;
       if (node is AnnotatedNode) {
         return node.documentationComment;
       }
     }
     return comment;
   }
 
   @override
-  VariableElement get element =>
-      _name != null ? (_name.staticElement as VariableElement) : null;
+  VariableElement get element => _name?.staticElement as VariableElement;
 
   @override
   Token get endToken {
     if (_initializer != null) {
       return _initializer.endToken;
     }
     return _name.endToken;
   }
 
   @override
@@ skipping 386 matching lines @@
 
   @override
   dynamic/*=E*/ accept/*<E>*/(AstVisitor/*<E>*/ visitor) =>
       visitor.visitYieldStatement(this);
 
   @override
   void visitChildren(AstVisitor visitor) {
     _expression?.accept(visitor);
   }
 }