Use readonly over getter for exposing events

Fixes #4164

src/browser/services/CharSizeService.ts

@@ -17,7 +17,7 @@ export class CharSizeService implements ICharSizeService {
   public get hasValidSize(): boolean { return this.width > 0 && this.height > 0; }
 
   private _onCharSizeChange = new EventEmitter<void>();
-  public get onCharSizeChange(): IEvent<void> { return this._onCharSizeChange.event; }
+  public readonly onCharSizeChange = this._onCharSizeChange.event;
 
   constructor(
     document: Document,

src/browser/services/RenderService.ts

@@ -40,13 +40,13 @@ export class RenderService extends Disposable implements IRenderService {
   };
 
   private _onDimensionsChange = new EventEmitter<IRenderDimensions>();
-  public get onDimensionsChange(): IEvent<IRenderDimensions> { return this._onDimensionsChange.event; }
+  public readonly onDimensionsChange =  this._onDimensionsChange.event;
   private _onRenderedViewportChange = new EventEmitter<{ start: number, end: number }>();
-  public get onRenderedViewportChange(): IEvent<{ start: number, end: number }> { return this._onRenderedViewportChange.event; }
+  public readonly onRenderedViewportChange = this._onRenderedViewportChange.event;
   private _onRender = new EventEmitter<{ start: number, end: number }>();
-  public get onRender(): IEvent<{ start: number, end: number }> { return this._onRender.event; }
+  public readonly onRender = this._onRender.event;
   private _onRefreshRequest = new EventEmitter<{ start: number, end: number }>();
-  public get onRefreshRequest(): IEvent<{ start: number, end: number }> { return this._onRefreshRequest.event; }
+  public readonly onRefreshRequest = this._onRefreshRequest.event;
 
   public get dimensions(): IRenderDimensions { return this._renderer.dimensions; }
 

src/browser/services/SelectionService.ts

@@ -112,13 +112,13 @@ export class SelectionService extends Disposable implements ISelectionService {
   private _oldSelectionEnd: [number, number] | undefined = undefined;
 
   private _onLinuxMouseSelection = this.register(new EventEmitter<string>());
-  public get onLinuxMouseSelection(): IEvent<string> { return this._onLinuxMouseSelection.event; }
+  public readonly onLinuxMouseSelection = this._onLinuxMouseSelection.event;
   private _onRedrawRequest = this.register(new EventEmitter<ISelectionRedrawRequestEvent>());
-  public get onRequestRedraw(): IEvent<ISelectionRedrawRequestEvent> { return this._onRedrawRequest.event; }
+  public readonly onRequestRedraw = this._onRedrawRequest.event;
   private _onSelectionChange = this.register(new EventEmitter<void>());
-  public get onSelectionChange(): IEvent<void> { return this._onSelectionChange.event; }
+  public readonly onSelectionChange = this._onSelectionChange.event;
   private _onRequestScrollLines = this.register(new EventEmitter<ISelectionRequestScrollLinesEvent>());
-  public get onRequestScrollLines(): IEvent<ISelectionRequestScrollLinesEvent> { return this._onRequestScrollLines.event; }
+  public readonly onRequestScrollLines = this._onRequestScrollLines.event;
 
   constructor(
     private readonly _element: HTMLElement,