refactor: use "as const" for constant mappings (#29000)

Co-authored-by: Milan Burda <milan.burda@gmail.com>

lib/browser/api/dialog.ts

@@ -2,10 +2,10 @@ import { app, BrowserWindow } from 'electron/main';
 import type { OpenDialogOptions, OpenDialogReturnValue, MessageBoxOptions, SaveDialogOptions, SaveDialogReturnValue, MessageBoxReturnValue, CertificateTrustDialogOptions } from 'electron/main';
 const dialogBinding = process._linkedBinding('electron_browser_dialog');
 
-const DialogType = {
-  OPEN: 'OPEN' as 'OPEN',
-  SAVE: 'SAVE' as 'SAVE'
-};
+enum DialogType {
+  OPEN = 'OPEN',
+  SAVE = 'SAVE'
+}
 
 enum SaveFileDialogProperties {
   createDirectory = 1 << 0,
@@ -72,7 +72,7 @@ const setupSaveDialogProperties = (properties: (keyof typeof SaveFileDialogPrope
   return dialogProperties;
 };
 
-const setupDialogProperties = (type: keyof typeof DialogType, properties: string[]): number => {
+const setupDialogProperties = (type: DialogType, properties: string[]): number => {
   if (type === DialogType.OPEN) {
     return setupOpenDialogProperties(properties as (keyof typeof OpenFileDialogProperties)[]);
   } else if (type === DialogType.SAVE) {

lib/browser/api/web-contents.ts

@@ -61,7 +61,7 @@ const PDFPageSizes: Record<string, ElectronInternal.MediaSize> = {
     width_microns: 279400,
     custom_display_name: 'Tabloid'
   }
-};
+} as const;
 
 // The minimum micron size Chromium accepts is that where:
 // Per printing/units.h:
@@ -110,7 +110,7 @@ const defaultPrintingSetting = {
   printerType: 2,
   title: undefined as string | undefined,
   url: undefined as string | undefined
-};
+} as const;
 
 // JavaScript implementations of WebContents.
 const binding = process._linkedBinding('electron_browser_web_contents');
@@ -192,7 +192,7 @@ WebContents.prototype.executeJavaScriptInIsolatedWorld = async function (worldId
 
 let pendingPromise: Promise<any> | undefined;
 WebContents.prototype.printToPDF = async function (options) {
-  const printSettings = {
+  const printSettings: Record<string, any> = {
     ...defaultPrintingSetting,
     requestID: getNextId()
   };