Support messages in assert().

lib/src/source_visitor.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 dart_style.src.source_visitor;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/generated/source.dart';
 
@@ skipping 143 matching lines @@
     soloSplit();
     token(node.asOperator);
     space();
     visit(node.type);
     builder.endSpan();
   }
 
   visitAssertStatement(AssertStatement node) {
     _simpleStatement(node, () {
       token(node.assertKeyword);
-      token(node.leftParenthesis);
-      soloZeroSplit();
-      visit(node.condition);
-      token(node.rightParenthesis);
+
+      var arguments = [node.condition];
+      if (node.message != null) arguments.add(node.message);
+
+      var visitor = new ArgumentListVisitor.forArguments(
+          this, node.leftParenthesis, node.rightParenthesis, arguments);
+      visitor.visit();
     });
   }
 
   visitAssignmentExpression(AssignmentExpression node) {
     builder.nestExpression();
 
     visit(node.leftHandSide);
     _visitAssignment(node.operator, node.rightHandSide);
 
     builder.unnest();
@@ skipping 2216 matching lines @@
   /// Gets the 1-based line number that the beginning of [token] lies on.
   int _startLine(Token token) => _lineInfo.getLocation(token.offset).lineNumber;
 
   /// Gets the 1-based line number that the end of [token] lies on.
   int _endLine(Token token) => _lineInfo.getLocation(token.end).lineNumber;
 
   /// Gets the 1-based column number that the beginning of [token] lies on.
   int _startColumn(Token token) =>
       _lineInfo.getLocation(token.offset).columnNumber;
 }