$OpenBSD$

index 4df1c07..048bfeb 100644
--- layout/base/nsPresShell.cpp.orig	Fri Feb 20 15:40:37 2015
+++ layout/base/nsPresShell.cpp	Fri Feb 20 15:40:37 2015
@@ -2616,10 +2616,11 @@ PresShell::FrameNeedsReflow(nsIFrame *aFrame, IntrinsicDirty aIntrinsicDirty,
                             nsFrameState aBitToAdd)
 {
   NS_PRECONDITION(aBitToAdd == NS_FRAME_IS_DIRTY ||
-                  aBitToAdd == NS_FRAME_HAS_DIRTY_CHILDREN,
+                  aBitToAdd == NS_FRAME_HAS_DIRTY_CHILDREN ||
+                  !aBitToAdd,
                   "Unexpected bits being added");
-  NS_PRECONDITION(aIntrinsicDirty != eStyleChange ||
-                  aBitToAdd == NS_FRAME_IS_DIRTY,
+  NS_PRECONDITION(!(aIntrinsicDirty == eStyleChange &&
+                    aBitToAdd == NS_FRAME_HAS_DIRTY_CHILDREN),
                   "bits don't correspond to style change reason");
 
   NS_ASSERTION(!mIsReflowing, "can't mark frame dirty during reflow");
@@ -2717,6 +2718,11 @@ PresShell::FrameNeedsReflow(nsIFrame *aFrame, IntrinsicDirty aIntrinsicDirty,
       } while (stack.Length() != 0);
     }
 
+    // Skip setting dirty bits up the tree if we weren't given a bit to add.
+    if (!aBitToAdd) {
+      continue;
+    }
+
     // Set NS_FRAME_HAS_DIRTY_CHILDREN bits (via nsIFrame::ChildIsDirty)
     // up the tree until we reach either a frame that's already dirty or
     // a reflow root.