Explicitly annotate (@flow/@noflow) every JS file (#1533)

It's the first step towards #1484 and also enables additional ESLint rules.

Author: IvanGoncharov

.eslintrc.yml

@@ -50,15 +50,15 @@ rules:
   #flowtype/no-flow-fix-me-comments: undecided
   #flowtype/no-mutable-array: undecided
   #flowtype/no-primitive-constructor-types: undecided
-  #flowtype/no-types-missing-file-annotation: undecided
+  flowtype/no-types-missing-file-annotation: error
   #flowtype/no-unused-expressions: undecided
   flowtype/no-weak-types: [error, {any: false}]
   flowtype/object-type-delimiter: off
   #flowtype/require-exact-type: undecided
   #flowtype/require-parameter-type: undecided
   #flowtype/require-return-type: undecided
   #flowtype/require-types-at-top: undecided
-  #flowtype/require-valid-file-annotation: undecided
+  flowtype/require-valid-file-annotation: [error, always, { annotationStyle: block }]
   #flowtype/require-variable-type: undecided
   flowtype/semi: off
   #flowtype/sort-keys: undecided

src/__fixtures__/index.js

@@ -1,3 +1,12 @@
+/**
+ * Copyright (c) 2018-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict
+ */
+
 import { join } from 'path';
 import { readFileSync } from 'fs';
 

src/error/__tests__/GraphQLError-test.js

@@ -3,6 +3,8 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
+ *
+ * @noflow
  */
 
 import { expect } from 'chai';

src/error/__tests__/locatedError-test.js

@@ -3,6 +3,8 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
+ *
+ * @noflow
  */
 
 import { expect } from 'chai';

src/error/__tests__/printError-test.js

@@ -3,6 +3,8 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
+ *
+ * @noflow
  */
 
 import { expect } from 'chai';

src/execution/__tests__/abstract-promise-test.js

@@ -3,6 +3,8 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
+ *
+ * @noflow
  */
 
 import { expect } from 'chai';

src/execution/__tests__/abstract-test.js

@@ -3,6 +3,8 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
+ *
+ * @noflow
  */
 
 import { expect } from 'chai';

src/execution/__tests__/directives-test.js

@@ -3,6 +3,8 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict
  */
 
 import { expect } from 'chai';

src/execution/__tests__/executor-test.js

@@ -3,6 +3,8 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
+ *
+ * @noflow
  */
 
 import { expect } from 'chai';

src/execution/__tests__/lists-test.js

@@ -3,6 +3,8 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
+ *
+ * @noflow
  */
 
 import { expect } from 'chai';