Remove more calls to safelyVisit methods

pkg/analyzer/lib/src/dart/element/element.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.element.element;
 
 import 'dart:collection';
 import 'dart:math' show min;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 2073 matching lines @@
 
   @override
   bool isAccessibleIn(LibraryElement library) {
     if (Identifier.isPrivateName(_name)) {
       return library == this.library;
     }
     return true;
   }
 
   /**
-   * If the given [child] is not `null`, use the given [visitor] to visit it.
-   */
-  void safelyVisitChild(Element child, ElementVisitor visitor) {
-    if (child != null) {
-      child.accept(visitor);
-    }
-  }
-
-  /**
    * Use the given [visitor] to visit all of the [children] in the given array.
    */
   void safelyVisitChildren(List<Element> children, ElementVisitor visitor) {
     if (children != null) {
       for (Element child in children) {
         child.accept(visitor);
       }
     }
   }
 
@@ skipping 928 matching lines @@
 
   @override
   void appendTo(StringBuffer buffer) {
     buffer.write("import ");
     (importedLibrary as LibraryElementImpl).appendTo(buffer);
   }
 
   @override
   void visitChildren(ElementVisitor visitor) {
     super.visitChildren(visitor);
-    safelyVisitChild(prefix, visitor);
+    prefix?.accept(visitor);
   }
 }
 
 /**
  * A concrete implementation of a [LabelElement].
  */
 class LabelElementImpl extends ElementImpl implements LabelElement {
   /**
    * A flag indicating whether this label is associated with a `switch`
    * statement.
@@ skipping 552 matching lines @@
 
   @override
   bool isUpToDate(int timeStamp) {
     Set<LibraryElement> visitedLibraries = new Set();
     return _safeIsUpToDate(this, timeStamp, visitedLibraries);
   }
 
   @override
   void visitChildren(ElementVisitor visitor) {
     super.visitChildren(visitor);
-    safelyVisitChild(_definingCompilationUnit, visitor);
+    _definingCompilationUnit?.accept(visitor);
     safelyVisitChildren(_exports, visitor);
     safelyVisitChildren(_imports, visitor);
     safelyVisitChildren(_parts, visitor);
   }
 
   /**
    * Recursively fills set of visible libraries for
    * [getVisibleElementsLibraries].
    */
   void _addVisibleLibraries(
@@ skipping 1275 matching lines @@
   @override
   void appendTo(StringBuffer buffer) {
     buffer.write(type);
     buffer.write(" ");
     buffer.write(displayName);
   }
 
   @override
   void visitChildren(ElementVisitor visitor) {
     super.visitChildren(visitor);
-    safelyVisitChild(_initializer, visitor);
+    _initializer?.accept(visitor);
   }
 }
 
 /**
  * A visitor that visit all the elements recursively and fill the given [map].
  */
 class _BuildOffsetToElementMap extends GeneralizingElementVisitor {
   final Map<int, Element> map;
 
   _BuildOffsetToElementMap(this.map);
 
   @override
   void visitElement(Element element) {
     int offset = element.nameOffset;
     if (offset != -1) {
       map[offset] = element;
     }
     super.visitElement(element);
   }
 }