Remove more calls to safelyVisit methods

pkg/analysis_server/lib/src/domains/analysis/navigation_dart.dart

 // Copyright (c) 2015, 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 domains.analysis.navigation_dart;
 
 import 'package:analysis_server/plugin/analysis/navigation/navigation_core.dart';
 import 'package:analysis_server/src/protocol_server.dart' as protocol;
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 109 matching lines @@
         prefixElement = element;
       }
       computer._addRegionForNode(name.prefix, prefixElement);
       // always constructor
       computer._addRegionForNode(name.identifier, element);
     } else {
       computer._addRegionForNode(name, element);
     }
     computer._addRegionForNode(node.constructorName, element);
     // arguments
-    _safelyVisit(node.arguments);
+    node.arguments?.accept(this);
   }
 
   @override
   visitAssignmentExpression(AssignmentExpression node) {
-    _safelyVisit(node.leftHandSide);
+    node.leftHandSide?.accept(this);
     computer._addRegionForToken(node.operator, node.bestElement);
-    _safelyVisit(node.rightHandSide);
+    node.rightHandSide?.accept(this);
   }
 
   @override
   visitBinaryExpression(BinaryExpression node) {
-    _safelyVisit(node.leftOperand);
+    node.leftOperand?.accept(this);
     computer._addRegionForToken(node.operator, node.bestElement);
-    _safelyVisit(node.rightOperand);
+    node.rightOperand?.accept(this);
   }
 
   @override
   visitCompilationUnit(CompilationUnit unit) {
     // prepare top-level nodes sorted by their offsets
     List<AstNode> nodes = <AstNode>[];
     nodes.addAll(unit.directives);
     nodes.addAll(unit.declarations);
     nodes.sort((a, b) {
       return a.offset - b.offset;
@@ skipping 93 matching lines @@
   @override
   visitRedirectingConstructorInvocation(RedirectingConstructorInvocation node) {
     Element element = node.staticElement;
     if (element != null && element.isSynthetic) {
       element = element.enclosingElement;
     }
     // add region
     computer._addRegionForToken(node.thisKeyword, element);
     computer._addRegionForNode(node.constructorName, element);
     // process arguments
-    _safelyVisit(node.argumentList);
+    node.argumentList?.accept(this);
   }
 
   @override
   visitSimpleIdentifier(SimpleIdentifier node) {
     if (node.parent is ConstructorDeclaration) {
       return;
     }
     Element element = node.bestElement;
     computer._addRegionForNode(node, element);
   }
 
   @override
   visitSuperConstructorInvocation(SuperConstructorInvocation node) {
     Element element = node.staticElement;
     if (element != null && element.isSynthetic) {
       element = element.enclosingElement;
     }
     // add region
     computer._addRegionForToken(node.superKeyword, element);
     computer._addRegionForNode(node.constructorName, element);
     // process arguments
-    _safelyVisit(node.argumentList);
+    node.argumentList?.accept(this);
   }
 
   void _addConstructorName(AstNode parent, ConstructorName node) {
     Element element = node.staticElement;
     if (element == null) {
       return;
     }
     // if a synthetic constructor, navigate to the class
     if (element.isSynthetic) {
       element = element.enclosingElement;
@@ skipping 26 matching lines @@
    * then add the navigation region from the [node] to the [element].
    */
   void _addUriDirectiveRegion(UriBasedDirective node, Element element) {
     if (element != null) {
       Source source = element.source;
       if (element.context.exists(source)) {
         computer._addRegionForNode(node.uri, element);
       }
     }
   }
-
-  void _safelyVisit(AstNode node) {
-    if (node != null) {
-      node.accept(this);
-    }
-  }
 }