--- a/layout/base/nsBidiPresUtils.cpp
+++ b/layout/base/nsBidiPresUtils.cpp
@@ -1311,16 +1311,24 @@ nsBidiPresUtils::ChildListMayRequireBidi
     // If unicode-bidi properties are present, we should do bidi resolution.
     nsStyleContext* sc = frame->StyleContext();
     if (GetBidiControl(sc) || GetBidiOverride(sc)) {
       return true;
     }
 
     if (IsBidiLeaf(frame)) {
       if (frame->IsTextFrame()) {
+        // If the frame already has a BidiDataProperty, we know we need to
+        // perform bidi resolution (even if no bidi content is NOW present --
+        // we might need to remove the property set by a previous reflow, if
+        // content has changed; see bug 1366623).
+        if (frame->Properties().Has(nsIFrame::BidiDataProperty())) {
+          return true;
+        }
+
         // Check whether the text frame has any RTL characters; if so, bidi
         // resolution will be needed.
         nsIContent* content = frame->GetContent();
         if (content != *aCurrContent) {
           *aCurrContent = content;
           const nsTextFragment* txt = content->GetText();
           if (txt->Is2b() && HasRTLChars(txt->Get2b(), txt->GetLength())) {
             return true;

--- a/layout/reftests/bidi/reftest.list
+++ b/layout/reftests/bidi/reftest.list
@@ -167,9 +167,9 @@ fuzzy-if(Android,254,557) == brackets-2a
 fuzzy-if(Android,254,231) == brackets-2c-rtl.html brackets-2c-rtl-ref.html
 == brackets-3a-ltr.html brackets-3a-ltr-ref.html
 == brackets-3a-rtl.html brackets-3a-rtl-ref.html
 == brackets-3b-ltr.html brackets-3b-ltr-ref.html
 == brackets-3b-rtl.html brackets-3b-rtl-ref.html
 fails-if(stylo) == 1217833-1.html 1217833-1-ref.html
 fails-if(stylo) == 1217833-2.html 1217833-2-ref.html
 == 1231175-1.html 1231175-1-ref.html
-fails == 1366623-1.html 1366623-1-ref.html
+== 1366623-1.html 1366623-1-ref.html