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

pkg/analyzer/test/generated/error_suppression_test.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.
 
 import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'resolver_test_case.dart';
@@ skipping 177 matching lines @@
     Source source = addSource('''
 int x = '';  //INVALID_ASSIGNMENT
 const y = x; //CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE
 ''');
     await computeAnalysisResult(source);
     assertErrors(source, [
       StaticTypeWarningCode.INVALID_ASSIGNMENT,
       CompileTimeErrorCode.CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE
     ]);
   }
+
+  test_ignore_for_file() async {
+    Source source = addSource('''
+int x = '';  //INVALID_ASSIGNMENT
+const y = x; //CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE
+// ignore_for_file: invalid_assignment
+''');
+    await computeAnalysisResult(source);
+    assertErrors(source,
+        [CompileTimeErrorCode.CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE]);
+  }
+
+  test_multiple_ignore_for_files() async {
+    Source source = addSource('''
+int x = '';  //INVALID_ASSIGNMENT
+const y = x; //CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE
+// ignore_for_file: invalid_assignment,const_initialized_with_non_constant_value
+''');
+    await computeAnalysisResult(source);
+    assertErrors(source, []);
+  }
+
+  test_ignore_for_file_whitespace_variant() async {
+    Source source = addSource('''
+//ignore_for_file:   const_initialized_with_non_constant_value , invalid_assignment
+int x = '';  //INVALID_ASSIGNMENT
+const y = x; //CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE
+''');
+    await computeAnalysisResult(source);
+    assertErrors(source, []);
+  }
 }