Switch from defer to Promise.withResolvers (#29078)

* Switch from defer to PromiseWithResolvers

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Add modernizr check

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Iterate

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

---------

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

test/unit-tests/components/structures/MatrixChat-test.tsx

@@ -21,7 +21,7 @@ import { completeAuthorizationCodeGrant } from "matrix-js-sdk/src/oidc/authorize
 import { logger } from "matrix-js-sdk/src/logger";
 import { OidcError } from "matrix-js-sdk/src/oidc/error";
 import { type BearerTokenResponse } from "matrix-js-sdk/src/oidc/validate";
-import { defer, type IDeferred, sleep } from "matrix-js-sdk/src/utils";
+import { sleep } from "matrix-js-sdk/src/utils";
 import {
     CryptoEvent,
     type DeviceVerificationStatus,
@@ -85,7 +85,7 @@ describe("<MatrixChat />", () => {
     const deviceId = "qwertyui";
     const accessToken = "abc123";
     const refreshToken = "def456";
-    let bootstrapDeferred: IDeferred<void>;
+    let bootstrapDeferred: PromiseWithResolvers<void>;
     // reused in createClient mock below
     const getMockClientMethods = () => ({
         ...mockClientMethodsUser(userId),
@@ -248,7 +248,7 @@ describe("<MatrixChat />", () => {
             {} as ValidatedServerConfig,
         );
 
-        bootstrapDeferred = defer();
+        bootstrapDeferred = Promise.withResolvers();
 
         await clearAllModals();
     });
@@ -1513,7 +1513,7 @@ describe("<MatrixChat />", () => {
                 jest.spyOn(MatrixJs, "createClient").mockReturnValue(client);
 
                 // intercept initCrypto and have it block until we complete the deferred
-                const initCryptoCompleteDefer = defer();
+                const initCryptoCompleteDefer = Promise.withResolvers<void>();
                 const initCryptoCalled = new Promise<void>((resolve) => {
                     client.initRustCrypto.mockImplementation(() => {
                         resolve();