re-add missing isStacking flag

browser/main/Detail/MarkdownNoteDetail.js

@@ -474,6 +474,7 @@ class MarkdownNoteDetail extends React.Component {
           value={note.content}
           storageKey={note.storage}
           noteKey={note.key}
+          isStacking={isStacking}
           linesHighlighted={note.linesHighlighted}
           onChange={this.handleUpdateContent}
           ignorePreviewPointerEvents={ignorePreviewPointerEvents}