src/vs/workbench/api/browser/mainThreadDocumentsAndEditors.ts/MainThreadDocumentsAndEditors/findTextEditorIdFor
class MainThreadDocumentsAndEditors:	findTextEditorIdFor(editorPane: IEditorPane): string | undefined {
		for (const [id, editor] of this._textEditors) {
			if (editor.matches(editorPane)) {
				return id;
			}
		}
		return undefined;
	}