Do not install the watchdog if the extension host is debuggable (#26445)

src/vs/workbench/api/node/extHost.protocol.ts

@@ -48,6 +48,7 @@ import { ITreeItem } from 'vs/workbench/parts/views/common/views';
 import { ThemeColor } from 'vs/platform/theme/common/themeService';
 
 export interface IEnvironment {
+	isExtensionDevelopmentDebug: boolean;
 	enableProposedApiForAll: boolean;
 	enableProposedApiFor: string | string[];
 	appSettingsHome: string;

src/vs/workbench/electron-browser/extensionHost.ts

@@ -291,9 +291,10 @@ export class ExtensionHostProcessWorker {
 
 	private createExtHostInitData(): TPromise<IInitData> {
 		return TPromise.join<any>([this.telemetryService.getTelemetryInfo(), this.extensionService.getExtensions()]).then(([telemetryInfo, extensionDescriptions]) => {
-			return <IInitData>{
+			let r: IInitData = {
 				parentPid: process.pid,
 				environment: {
+					isExtensionDevelopmentDebug: this.isExtensionDevelopmentDebug,
 					appSettingsHome: this.environmentService.appSettingsHome,
 					disableExtensions: this.environmentService.disableExtensions,
 					userExtensionsHome: this.environmentService.extensionsPath,
@@ -308,6 +309,7 @@ export class ExtensionHostProcessWorker {
 				configuration: this.configurationService.getConfigurationData(),
 				telemetryInfo
 			};
+			return r;
 		});
 	}
 

src/vs/workbench/node/extensionHostMain.ts

@@ -54,8 +54,10 @@ export class ExtensionHostMain {
 		errors.setUnexpectedErrorHandler(err => mainThreadErrors.onUnexpectedExtHostError(errors.transformErrorForSerialization(err)));
 
 		// Configure the watchdog to kill our process if the JS event loop is unresponsive for more than 10s
+		if (!initData.environment.isExtensionDevelopmentDebug) {
 			watchdog.start(10000);
 		}
+	}
 
 	public start(): TPromise<void> {
 		return this._extensionService.onReady()