Bug 1433591: Update the style of child anon box wrapper after owned anon boxes. r=bz

Since the former could inherit from the latter.

Test incoming in a followup.

MozReview-Commit-ID: LJjprcyjDyU

layout/base/ServoRestyleManager.cpp

@@ -970,14 +970,17 @@ ServoRestyleManager::ProcessPostTraversal(
   // modify the styles of the kids, and the child traversal above would just
   // clobber those modifications.
   if (styleFrame) {
-    // Process anon box wrapper frames before ::first-line bits.
-    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.
+      // otherwise ProcessPostTraversalForText could clobber first-letter
+      // styles, for example.
       styleFrame->UpdateStyleOfOwnedAnonBoxes(childrenRestyleState);
+    }
+    // Process anon box wrapper frames before ::first-line bits, but _after_
+    // owned anon boxes, since the children wrapper anon boxes could be
+    // inheriting from our own owned anon boxes.
+    childrenRestyleState.ProcessWrapperRestyles(styleFrame);
+    if (wasRestyled) {
       UpdateFramePseudoElementStyles(styleFrame, childrenRestyleState);
     } else if (traverseElementChildren &&
                styleFrame->IsFrameOfType(nsIFrame::eBlockFrame)) {