[formatter] Utilize available CPU cores.

Drive-by-fix: Use uppercase naming for constants as per the JavaScript
style guide.

Change-Id: I7b9adb7ec1067ab79319d79dd68668a53bf29f46
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2514437
Reviewed-by: Paul Lewis <aerotwist@chromium.org>
Commit-Queue: Paul Lewis <aerotwist@chromium.org>
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>

front_end/formatter/FormatterWorkerPool.js

@@ -4,7 +4,7 @@
 
 import * as Common from '../common/common.js';
 
-const MaxWorkers = 2;
+const MAX_WORKERS = Math.min(2, navigator.hardwareConcurrency - 1);
 
 /** @type {!FormatterWorkerPool} */
 let formatterWorkerPoolInstance;
@@ -47,7 +47,7 @@ export class FormatterWorkerPool {
     }
 
     let freeWorker = [...this._workerTasks.keys()].find(worker => !this._workerTasks.get(worker));
-    if (!freeWorker && this._workerTasks.size < MaxWorkers) {
+    if (!freeWorker && this._workerTasks.size < MAX_WORKERS) {
       freeWorker = this._createWorker();
     }
     if (!freeWorker) {