[react-native-url-polyfill] New definition (#4246)

* add initial definition

* add some api tests

definitions/npm/react-native-url-polyfill_v1.x.x/flow_v0.83.x-/react-native-url-polyfill_v1.x.x.js

@@ -0,0 +1,13 @@
+declare module 'react-native-url-polyfill' {
+  import typeof { URL as NativeURL, URLSearchParams as NativeURLSearchParams } from 'url';
+
+  declare export var URL: NativeURL;
+
+  declare export var URLSearchParams: NativeURLSearchParams;
+
+  declare export function setupURLPolyfill(): void;
+}
+
+declare module 'react-native-url-polyfill/auto' {
+  declare module.exports: void;
+}

definitions/npm/react-native-url-polyfill_v1.x.x/flow_v0.83.x-/test_react-native-url-polyfill_v1.x.x.js

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+// @flow
+import { describe, it } from 'flow-typed-test';
+import { setupURLPolyfill, URL, URLSearchParams } from 'react-native-url-polyfill';
+import auto from 'react-native-url-polyfill/auto';
+
+describe('react-native-url-polyfill', () => {
+  it('simple usage', () => {
+    // It's an auto running script
+    (auto: void);
+  });
+
+  it('flexible usage', () => {
+    setupURLPolyfill();
+
+    // $FlowExpectedError[extra-arg] takes no args
+    setupURLPolyfill('test');
+  });
+
+  it('convenient usage', () => {
+    const url = new URL('https://github.com');
+    const searchParams = new URLSearchParams('q=GitHub');
+
+    // Has the same methods as node `url`
+    // $FlowExpectedError[extra-arg]
+    url.toJSON('test');
+    // $FlowExpectedError[incompatible-call]
+    searchParams.delete();
+  });
+});