Bug 1428164: Restyle owned anon boxes after processing children. r=bz

MozReview-Commit-ID: 4QcJPY9hkSm

layout/base/ServoRestyleManager.cpp

@@ -909,7 +909,6 @@ ServoRestyleManager::ProcessPostTraversal(
 
     if (styleFrame) {
       UpdateAdditionalStyleContexts(styleFrame, aRestyleState);
-      styleFrame->UpdateStyleOfOwnedAnonBoxes(childrenRestyleState);
     }
 
     if (!aElement->GetParent()) {
@@ -973,6 +972,10 @@ ServoRestyleManager::ProcessPostTraversal(
     childrenRestyleState.ProcessWrapperRestyles(styleFrame);
 
     if (wasRestyled) {
+      // Make sure to update anon boxes and pseudo bits after updating text,
+      // otherwise we could clobber first-letter styles from
+      // ProcessPostTraversalForText, for example.
+      styleFrame->UpdateStyleOfOwnedAnonBoxes(childrenRestyleState);
       UpdateFramePseudoElementStyles(styleFrame, childrenRestyleState);
     } else if (traverseElementChildren &&
                styleFrame->IsFrameOfType(nsIFrame::eBlockFrame)) {