Analyzer: add ignore_for_file comment that ignores a type of problem for the whole file; add tests.

pkg/analyzer/test/src/task/dart_test.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 analyzer.test.src.task.dart_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_resolution_map.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
@@ skipping 4342 matching lines @@
     expectMutated(body, main.parameters[2], true, true);
     expectMutated(body, main.parameters[3], true, true);
   }
 }
 
 @reflectiveTest
 class ScanDartTaskTest extends _AbstractDartTaskTest {
   test_ignore_info() {
     _performScanTask('''
 //ignore: error_code
+//ignore_for_file: error_code
 var x = '';
 foo(); // ignore:   error_code_2
 bar(); //ignore: error_code, error_code_2
+// ignore_for_file:  error_code_2, error_code_3
 ''');
 
     IgnoreInfo info = outputs[IGNORE_INFO];
     expect(info.ignores.keys, hasLength(3));
     expect(info.ignores[1].first, 'error_code');
-    expect(info.ignores[3].first, 'error_code_2');
-    expect(info.ignores[4], unorderedEquals(['error_code', 'error_code_2']));
+    expect(info.ignores[4].first, 'error_code_2');
+    expect(info.ignores[5], unorderedEquals(['error_code', 'error_code_2']));
+    expect(info.ignoreForFiles,
+        unorderedEquals(['error_code', 'error_code_2', 'error_code_3']));
   }
 
   test_perform_errors() {
     _performScanTask('import "');
     expect(outputs, hasLength(4));
     expect(outputs[LINE_INFO], isNotNull);
     expect(outputs[SCAN_ERRORS], hasLength(1));
     expect(outputs[TOKEN_STREAM], isNotNull);
     IgnoreInfo ignoreInfo = outputs[IGNORE_INFO];
     expect(ignoreInfo, isNotNull);
@@ skipping 892 matching lines @@
   /**
    * Fill [errorListener] with [result] errors in the current [task].
    */
   void _fillErrorListener(ResultDescriptor<List<AnalysisError>> result) {
     List<AnalysisError> errors = task.outputs[result] as List<AnalysisError>;
     expect(errors, isNotNull, reason: result.name);
     errorListener = new GatheringErrorListener();
     errorListener.addAll(errors);
   }
 }