limit marketplace queries to 200 chars

fixes #10384

src/vs/workbench/parts/extensions/electron-browser/extensionsViewlet.ts

@@ -237,7 +237,7 @@ export class ExtensionsViewlet extends Viewlet implements IExtensionsViewlet {
 		}
 
 		if (query.value) {
-			options = assign(options, { text: query.value });
+			options = assign(options, { text: query.value.substr(0, 200) });
 		}
 
 		return this.extensionsWorkbenchService.queryGallery(options)