--- a/layout/base/RestyleManager.cpp
+++ b/layout/base/RestyleManager.cpp
@@ -3671,18 +3671,19 @@ ElementRestyler::MaybeReframeForBeforePs
   // can't have generated content.
   nsContainerFrame* cif;
   if (!aStyleContext->GetPseudo() &&
       ((aGenConParentFrame->GetStateBits() & NS_FRAME_MAY_HAVE_GENERATED_CONTENT) ||
        // Our content insertion frame might have gotten flagged.
        ((cif = aGenConParentFrame->GetContentInsertionFrame()) &&
         (cif->GetStateBits() & NS_FRAME_MAY_HAVE_GENERATED_CONTENT)))) {
     // Check for a ::before pseudo style and the absence of a ::before content,
-    // but only if aFrame is null or is the first continuation.
-    if (!aFrame || !aFrame->GetPrevContinuation()) {
+    // but only if aFrame is null or is the first continuation/ib-split.
+    if (!aFrame ||
+        nsLayoutUtils::IsFirstContinuationOrIBSplitSibling(aFrame)) {
       // Checking for a ::before frame is cheaper than getting the
       // ::before style context.
       if (!nsLayoutUtils::GetBeforeFrameForContent(aGenConParentFrame, aContent) &&
           nsLayoutUtils::HasPseudoStyle(aContent, aStyleContext,
                                         nsCSSPseudoElements::ePseudo_before,
                                         mPresContext)) {
         // Have to create the new ::before frame.
         LOG_RESTYLE("MaybeReframeForBeforePseudo, appending "
@@ -3717,18 +3718,19 @@ ElementRestyler::MaybeReframeForAfterPse
   // can't have generated content.
   nsContainerFrame* cif;
   if (!aStyleContext->GetPseudo() &&
       ((aGenConParentFrame->GetStateBits() & NS_FRAME_MAY_HAVE_GENERATED_CONTENT) ||
        // Our content insertion frame might have gotten flagged.
        ((cif = aGenConParentFrame->GetContentInsertionFrame()) &&
         (cif->GetStateBits() & NS_FRAME_MAY_HAVE_GENERATED_CONTENT)))) {
     // Check for an ::after pseudo style and the absence of an ::after content,
-    // but only if aFrame is null or is the last continuation.
-    if (!aFrame || !aFrame->GetNextContinuation()) {
+    // but only if aFrame is null or is the last continuation/ib-split.
+    if (!aFrame ||
+        !nsLayoutUtils::GetNextContinuationOrIBSplitSibling(aFrame)) {
       // Checking for an ::after frame is cheaper than getting the
       // ::after style context.
       if (!nsLayoutUtils::GetAfterFrameForContent(aGenConParentFrame, aContent) &&
           nsLayoutUtils::HasPseudoStyle(aContent, aStyleContext,
                                         nsCSSPseudoElements::ePseudo_after,
                                         mPresContext)) {
         // Have to create the new ::after frame.
         LOG_RESTYLE("MaybeReframeForAfterPseudo, appending "

--- a/layout/base/tests/test_frame_reconstruction_for_pseudo_elements.html
+++ b/layout/base/tests/test_frame_reconstruction_for_pseudo_elements.html
@@ -30,17 +30,17 @@ https://bugzilla.mozilla.org/show_bug.cg
   </style>
   <script type="application/javascript">
 
   /** Test for Bug 1110277 **/
 
   SimpleTest.waitForExplicitFinish();
 
   function run() {
-    runtest("first line test", "#firstlinetest > .testspan", { todo: true });
+    runtest("first line test", "#firstlinetest > .testspan", {});
     runtest("after test", "#aftertest > .testspan", { todo: true });
     SimpleTest.finish();
   }
 
   function runtest(description, selector, flags) {
     var utils = SpecialPowers.getDOMWindowUtils(window);
     var span = document.querySelector(selector);
     var cs = getComputedStyle(span, "");