src/vs/workbench/contrib/files/browser/editors/textFileEditor.ts/TextFileEditor/updateReadonly
class TextFileEditor:	private updateReadonly(input: FileEditorInput): void {
		const control = this.getControl();
		if (control) {
			control.updateOptions({ readOnly: input.hasCapability(EditorInputCapabilities.Readonly) });
		}
	}