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

Index: pkg/analyzer/test/generated/error_suppression_test.dart
diff --git a/pkg/analyzer/test/generated/error_suppression_test.dart b/pkg/analyzer/test/generated/error_suppression_test.dart
index 62d525e9bd70bf93cb18011804d774354fd2cd64..ec43f49335dce2b10ec9c7071c63392c9e11894f 100644
--- a/pkg/analyzer/test/generated/error_suppression_test.dart
+++ b/pkg/analyzer/test/generated/error_suppression_test.dart
@@ -195,4 +195,35 @@ const y = x; //CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE
       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, []);
+  }
 }