Switch to native Promise.allSettled

As discussed in code review, this is widely available.  Update tsconfig.json to recognize it.

packages/workbox-core/src/_private.ts

@@ -7,7 +7,6 @@
 */
 
 // We either expose defaults or we expose every named export.
-import {allSettled} from './_private/allSettled.js';
 import {assert} from './_private/assert.js';
 import {cacheNames} from './_private/cacheNames.js';
 import {cacheMatchIgnoreParams} from './_private/cacheMatchIgnoreParams.js';
@@ -26,7 +25,6 @@ import {WorkboxError} from './_private/WorkboxError.js';
 import './_version.js';
 
 export {
-  allSettled,
   assert,
   cacheMatchIgnoreParams,
   cacheNames,

packages/workbox-strategies/src/StrategyHandler.ts

@@ -6,10 +6,6 @@
   https://opensource.org/licenses/MIT.
 */
 
-import {
-  allSettled,
-  PromiseRejection,
-} from 'workbox-core/_private/allSettled.js';
 import {assert} from 'workbox-core/_private/assert.js';
 import {cacheMatchIgnoreParams} from 'workbox-core/_private/cacheMatchIgnoreParams.js';
 import {Deferred} from 'workbox-core/_private/Deferred.js';
@@ -566,10 +562,10 @@ class StrategyHandler {
   async doneWaiting(): Promise<void> {
     while (this._extendLifetimePromises.length) {
       const promises = this._extendLifetimePromises.splice(0);
-      const result = await allSettled(promises);
+      const result = await Promise.allSettled(promises);
       const firstRejection = result.find((i) => i.status === 'rejected');
       if (firstRejection) {
-        throw (firstRejection as PromiseRejection).reason;
+        throw (firstRejection as PromiseRejectedResult).reason;
       }
     }
   }

tsconfig.json

@@ -2,7 +2,7 @@
   "compilerOptions": {
     "composite": true,
     "declaration": true,
-    "lib": ["es2017", "webworker"],
+    "lib": ["es2020", "webworker"],
     "module": "esnext",
     "moduleResolution": "node",
     "noFallthroughCasesInSwitch": true,