From c7688ac21f60a89fb1cfdcc5e186d3b65ddd4184 Mon Sep 17 00:00:00 2001
From: Mats Palmgren <mats@mozilla.com>
Date: Thu, 15 Feb 2018 18:38:03 +0100
Subject: [PATCH] Bug 1432853 - Disable 'page-break-inside:avoid' on abs.pos.
 frames for now.  r=dholbert

---
 layout/generic/nsAbsoluteContainingBlock.cpp | 12 +++---------
 layout/generic/nsFrame.cpp                   | 10 ++++++++++
 layout/generic/nsFrame.h                     |  6 +-----
 3 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/layout/generic/nsAbsoluteContainingBlock.cpp b/layout/generic/nsAbsoluteContainingBlock.cpp
index 78822b04d0fc..e87e089ca459 100644
--- a/layout/generic/nsAbsoluteContainingBlock.cpp
+++ b/layout/generic/nsAbsoluteContainingBlock.cpp
@@ -167,17 +167,11 @@ nsAbsoluteContainingBlock::Reflow(nsContainerFrame*        aDelegatingFrame,
       nsReflowStatus kidStatus;
       ReflowAbsoluteFrame(aDelegatingFrame, aPresContext, aReflowInput, cb,
                           aFlags, kidFrame, kidStatus, aOverflowAreas);
+      MOZ_ASSERT(!kidStatus.IsInlineBreakBefore(),
+                 "ShouldAvoidBreakInside should prevent this from happening");
       nsIFrame* nextFrame = kidFrame->GetNextInFlow();
-      if ((kidStatus.IsInlineBreakBefore() ||
-           !kidStatus.IsFullyComplete()) &&
+      if (!kidStatus.IsFullyComplete() &&
           aDelegatingFrame->IsFrameOfType(nsIFrame::eCanContainOverflowContainers)) {
-        // XXX it's unclear how we should handle 'page-break-inside:avoid' on
-        // abs.pos. boxes -- ignore it for now by setting the status to
-        // Incomplete (which will probably fragment it).
-        if (kidStatus.IsInlineBreakBefore()) {
-          kidStatus.Reset();
-          kidStatus.SetIncomplete();
-        }
         // Need a continuation
         if (!nextFrame) {
           nextFrame =
diff --git a/layout/generic/nsFrame.cpp b/layout/generic/nsFrame.cpp
index 233bb2d0b55c..c1ffdc8624d5 100644
--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -9704,6 +9704,16 @@ nsFrame::ConsiderChildOverflow(nsOverflowAreas& aOverflowAreas,
                            aChildFrame->GetPosition());
 }
 
+bool
+nsFrame::ShouldAvoidBreakInside(const ReflowInput& aReflowInput) const
+{
+  const auto* disp = StyleDisplay();
+  return !aReflowInput.mFlags.mIsTopOfPage &&
+    NS_STYLE_PAGE_BREAK_AVOID == disp->mBreakInside &&
+    !(HasAnyStateBits(NS_FRAME_OUT_OF_FLOW) && IsAbsolutelyPositioned(disp)) &&
+    !GetPrevInFlow();
+}
+
 /**
  * This function takes a frame that is part of a block-in-inline split,
  * and _if_ that frame is an anonymous block created by an ib split it
diff --git a/layout/generic/nsFrame.h b/layout/generic/nsFrame.h
index 1e6cb567e878..cbec963bca2c 100644
--- a/layout/generic/nsFrame.h
+++ b/layout/generic/nsFrame.h
@@ -473,11 +473,7 @@ public:
   /**
    * @return true if we should avoid a page/column break in this frame.
    */
-  bool ShouldAvoidBreakInside(const ReflowInput& aReflowInput) const {
-    return !aReflowInput.mFlags.mIsTopOfPage &&
-           NS_STYLE_PAGE_BREAK_AVOID == StyleDisplay()->mBreakInside &&
-           !GetPrevInFlow();
-  }
+  bool ShouldAvoidBreakInside(const ReflowInput& aReflowInput) const;
 
 #ifdef DEBUG
   /**