Migrate WebUSB LayoutTests into external/wpt

third_party/WebKit/LayoutTests/usb/resources/usb-helpers.js

-'use strict';
-
-function usb_test(func, name, properties) {
-  promise_test(() => {
-    return navigator.usb.test.initialize().then(() => {
-      let testResult = func();
-      let cleanup = () => {
-        navigator.usb.test.reset();
-      };
-      testResult.then(cleanup, cleanup);
-      return testResult;
-    });
-  }, name, properties);
-}
-
-function assertRejectsWithError(promise, name, message) {
-  return promise.then(() => {
-    assert_unreached('expected promise to reject with ' + name);
-  }, error => {
-    assert_equals(error.name, name);
-    if (message !== undefined)
-      assert_equals(error.message, message);
-  });
-}
-
-function assertDeviceInfoEquals(usbDevice, deviceInit) {
-  for (var property in deviceInit) {
-    if (property == 'activeConfigurationValue') {
-      if (deviceInit.activeConfigurationValue == 0) {
-        assert_equals(usbDevice.configuration, null);
-      } else {
-        assert_equals(usbDevice.configuration.configurationValue,
-                      deviceInit.activeConfigurationValue);
-      }
-    } else if (Array.isArray(deviceInit[property])) {
-      assert_equals(usbDevice[property].length, deviceInit[property].length);
-      for (var i = 0; i < usbDevice[property].length; ++i)
-        assertDeviceInfoEquals(usbDevice[property][i], deviceInit[property][i]);
-    } else {
-      assert_equals(usbDevice[property], deviceInit[property], property);
-    }
-  }
-}
-
-// TODO(reillyg): Remove when jyasskin upstreams this to testharness.js:
-// https://crbug.com/509058.
-function callWithKeyDown(functionCalledOnKeyPress) {
-  return new Promise(resolve => {
-    function onKeyPress() {
-      document.removeEventListener('keypress', onKeyPress, false);
-      resolve(functionCalledOnKeyPress());
-    }
-    document.addEventListener('keypress', onKeyPress, false);
-
-    eventSender.keyDown(' ', []);
-  });
-}
-
-function runGarbageCollection() {
-  // Run gc() as a promise.
-  return new Promise((resolve, reject) => {
-    GCController.collect();
-    setTimeout(resolve, 0);
-  });
-}