Add readonly to a few more properties (microsoft#165563)

Add readonly to a few properties

Author: mjbvz

src/vs/base/browser/ui/actionbar/actionbar.ts

@@ -84,19 +84,19 @@ export class ActionBar extends Disposable implements IActionRunner {
 
 	// Elements
 	domNode: HTMLElement;
-	protected actionsList: HTMLElement;
+	protected readonly actionsList: HTMLElement;
 
-	private _onDidBlur = this._register(new Emitter<void>());
+	private readonly _onDidBlur = this._register(new Emitter<void>());
 	readonly onDidBlur = this._onDidBlur.event;
 
-	private _onDidCancel = this._register(new Emitter<void>({ onWillAddFirstListener: () => this.cancelHasListener = true }));
+	private readonly _onDidCancel = this._register(new Emitter<void>({ onWillAddFirstListener: () => this.cancelHasListener = true }));
 	readonly onDidCancel = this._onDidCancel.event;
 	private cancelHasListener = false;
 
-	private _onDidRun = this._register(new Emitter<IRunEvent>());
+	private readonly _onDidRun = this._register(new Emitter<IRunEvent>());
 	readonly onDidRun = this._onDidRun.event;
 
-	private _onWillRun = this._register(new Emitter<IRunEvent>());
+	private readonly _onWillRun = this._register(new Emitter<IRunEvent>());
 	readonly onWillRun = this._onWillRun.event;
 
 	constructor(container: HTMLElement, options: IActionBarOptions = {}) {