Begin adding top-level function declaration support to AstBuilder.

pkg/analyzer/test/generated/parser_test.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.test.generated.parser_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_ast_factory.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
@@ skipping 13382 matching lines @@
     createParser('const int x = 0;');
     CompilationUnitMember member = parseFullCompilationUnitMember();
     expect(member, isNotNull);
     assertNoErrors();
     expect(member, new isInstanceOf<TopLevelVariableDeclaration>());
     TopLevelVariableDeclaration declaration = member;
     expect(declaration.semicolon, isNotNull);
     expect(declaration.variables, isNotNull);
   }
 
+  void test_parseCompilationUnitMember_expressionFunctionBody_tokens() {
+    createParser('f() => 0;');
+    var f = parseFullCompilationUnitMember() as FunctionDeclaration;
+    var body = f.functionExpression.body as ExpressionFunctionBody;
+    expect(body.functionDefinition.lexeme, '=>');
+    expect(body.semicolon.lexeme, ';');
+  }
+
   void test_parseCompilationUnitMember_finalVariable() {
     createParser('final x = 0;');
     CompilationUnitMember member = parseFullCompilationUnitMember();
     expect(member, isNotNull);
     assertNoErrors();
     expect(member, new isInstanceOf<TopLevelVariableDeclaration>());
     TopLevelVariableDeclaration declaration = member;
     expect(declaration.semicolon, isNotNull);
     expect(declaration.variables, isNotNull);
   }
@@ skipping 1096 matching lines @@
     expect(typeAlias.name, isNotNull);
     expect(typeAlias.typeParameters, isNull);
     expect(typeAlias.semicolon, isNotNull);
     GenericFunctionType functionType = typeAlias.functionType;
     expect(functionType, isNotNull);
     expect(functionType.parameters, isNotNull);
     expect(functionType.returnType, isNotNull);
     expect(functionType.typeParameters, isNull);
   }
 }