Include CompilationUnit begin/endToken(s) with Fasta.

pkg/analyzer/lib/src/fasta/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 1036 matching lines @@
         name,
         ast.functionExpression(typeParameters, parameters, body)));
   }
 
   @override
   void endTopLevelDeclaration(Token token) {
     debugEvent("TopLevelDeclaration");
   }
 
   @override
-  void endCompilationUnit(int count, Token token) {
+  void beginCompilationUnit(Token token) {
+    push(token);
+  }
+
+  @override
+  void endCompilationUnit(int count, Token endToken) {
     debugEvent("CompilationUnit");
-    analyzer.Token beginToken = null; // TODO(paulberry)
+    List<Object> elements = popList(count);
+    Token beginToken = pop();
+
     ScriptTag scriptTag = null;
     var directives = <Directive>[];
     var declarations = <CompilationUnitMember>[];
-    analyzer.Token endToken = null; // TODO(paulberry)
-    List<Object> elements = popList(count);
     if (elements != null) {
       for (AstNode node in elements) {
         if (node is ScriptTag) {
           scriptTag = node;
         } else if (node is Directive) {
           directives.add(node);
         } else if (node is CompilationUnitMember) {
           declarations.add(node);
         } else {
           internalError(
               'Unrecognized compilation unit member: ${node.runtimeType}');
         }
       }
     }
+
     push(ast.compilationUnit(
         beginToken, scriptTag, directives, declarations, endToken));
   }
 
   void endImport(Token importKeyword, Token deferredKeyword, Token asKeyword,
       Token semicolon) {
     debugEvent("Import");
     List<Combinator> combinators = pop();
     SimpleIdentifier prefix;
     if (asKeyword != null) prefix = pop();
@@ skipping 775 matching lines @@
       } else if (identical('static', s)) {
         staticKeyword = token;
       } else if (identical('var', s)) {
         finalConstOrVarKeyword = token;
       } else {
         internalError('Unhandled modifier: $s');
       }
     }
   }
 }