Parse assert statements with Fasta.

pkg/front_end/lib/src/fasta/analyzer/ast_builder.dart

 // Copyright (c) 2016, 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 fasta.analyzer.ast_builder;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/dart/ast/ast_factory.dart' show AstFactory;
 import 'package:analyzer/dart/ast/standard_ast_factory.dart' as standard;
 import 'package:analyzer/dart/ast/token.dart' as analyzer show Token;
@@ skipping 561 matching lines @@
   void handleType(Token beginToken, Token endToken) {
     debugEvent("Type");
     TypeArgumentList arguments = pop();
     Identifier name = pop();
     // TODO(paulberry,ahe): what if the type doesn't resolve to a class
     // element?  Try to share code with BodyBuilder.builderToFirstExpression.
     KernelClassElement cls = name.staticElement;
     push(ast.typeName(name, arguments)..type = cls?.rawType);
   }
 
+  @override
+  void handleAssertStatement(Token assertKeyword, Token leftParenthesis,
+      Token comma, Token rightParenthesis, Token semicolon) {
+    debugEvent("AssertStatement");
+    Expression message = popIfNotNull(comma);
+    Expression condition = pop();
+    push(ast.assertStatement(
+        toAnalyzerToken(assertKeyword),
+        toAnalyzerToken(leftParenthesis),
+        condition,
+        toAnalyzerToken(comma),
+        message,
+        toAnalyzerToken(rightParenthesis),
+        toAnalyzerToken(semicolon)));
+  }
+
   void handleAsOperator(Token operator, Token endToken) {
     debugEvent("AsOperator");
     TypeAnnotation type = pop();
     Expression expression = pop();
     push(ast.asExpression(expression, toAnalyzerToken(operator), type));
   }
 
   void handleIsOperator(Token operator, Token not, Token endToken) {
     debugEvent("IsOperator");
     TypeAnnotation type = pop();
@@ skipping 1054 matching lines @@
       } else if (identical('static', s)) {
         staticKeyword = token;
       } else if (identical('var', s)) {
         finalConstOrVarKeyword = token;
       } else {
         internalError('Unhandled modifier: $s');
       }
     }
   }
 }