Bug 1700472 - Remove -moz-scrolled-page-sequence. r=dholbert

This is needed for bug 1700379, because otherwise we create a reference
frame with the root's scrolled content (the
::-moz-scrolled-page-sequence), and that breaks some display list
invariants.

Always create a canvas frame instead, (doesn't matter when printing
since we print off the page sequence frame directly), and create a
single ::-moz-page-sequence box.

Differential Revision: https://phabricator.services.mozilla.com/D109512

layout/base/nsCSSFrameConstructor.cpp

@@ -2471,6 +2471,7 @@ void nsCSSFrameConstructor::SetUpDocElementContainingBlock(
   Print presentation, non-XUL
 
       ViewportFrame
+        nsCanvasFrame
           nsPageSequenceFrame
             PrintedSheetFrame
               nsPageFrame
@@ -2483,6 +2484,7 @@ void nsCSSFrameConstructor::SetUpDocElementContainingBlock(
 
       ViewportFrame
         nsHTMLScrollFrame
+          nsCanvasFrame
             nsPageSequenceFrame
               PrintedSheetFrame
                 nsPageFrame
@@ -2543,9 +2545,7 @@ void nsCSSFrameConstructor::SetUpDocElementContainingBlock(
   ComputedStyle* viewportPseudoStyle = viewportFrame->Style();
 
   nsContainerFrame* rootFrame = nullptr;
-  PseudoStyleType rootPseudo;
 
-  if (!isPaginated) {
 #ifdef MOZ_XUL
   if (aDocElement->IsXULElement()) {
     // pass a temporary stylecontext, the correct one will be set later
@@ -2558,14 +2558,8 @@ void nsCSSFrameConstructor::SetUpDocElementContainingBlock(
     mHasRootAbsPosContainingBlock = true;
   }
 
-    rootPseudo = PseudoStyleType::canvas;
+  PseudoStyleType rootPseudo = PseudoStyleType::canvas;
   mDocElementContainingBlock = rootFrame;
-  } else {
-    // Create a page sequence frame
-    rootFrame = mPageSequenceFrame =
-        NS_NewPageSequenceFrame(mPresShell, viewportPseudoStyle);
-    rootPseudo = PseudoStyleType::pageSequence;
-  }
 
   // --------- IF SCROLLABLE WRAP IN SCROLLFRAME --------
 
@@ -2595,13 +2589,7 @@ void nsCSSFrameConstructor::SetUpDocElementContainingBlock(
     rootPseudoStyle = styleSet->ResolveInheritingAnonymousBoxStyle(
         rootPseudo, viewportPseudoStyle);
   } else {
-    if (rootPseudo == PseudoStyleType::canvas) {
     rootPseudo = PseudoStyleType::scrolledCanvas;
-    } else {
-      NS_ASSERTION(rootPseudo == PseudoStyleType::pageSequence,
-                   "Unknown root pseudo");
-      rootPseudo = PseudoStyleType::scrolledPageSequence;
-    }
 
     // Build the frame. We give it the content we are wrapping which is the
     // document element, the root frame, the parent view port frame, and we
@@ -2635,11 +2623,22 @@ void nsCSSFrameConstructor::SetUpDocElementContainingBlock(
   }
 
   if (isPaginated) {
+    // Create a page sequence frame
+    {
+      RefPtr<ComputedStyle> pageSequenceStyle =
+        styleSet->ResolveInheritingAnonymousBoxStyle(
+          PseudoStyleType::pageSequence, viewportPseudoStyle);
+      mPageSequenceFrame =
+          NS_NewPageSequenceFrame(mPresShell, pageSequenceStyle);
+      mPageSequenceFrame->Init(aDocElement, rootFrame, nullptr);
+      SetInitialSingleChild(rootFrame, mPageSequenceFrame);
+    }
+
     // Create the first printed sheet frame, as the sole child (for now) of our
-    // page sequence frame (rootFrame).
+    // page sequence frame (mPageSequenceFrame).
     auto* printedSheetFrame =
-        ConstructPrintedSheetFrame(mPresShell, rootFrame, nullptr);
+        ConstructPrintedSheetFrame(mPresShell, mPageSequenceFrame, nullptr);
-    SetInitialSingleChild(rootFrame, printedSheetFrame);
+    SetInitialSingleChild(mPageSequenceFrame, printedSheetFrame);
 
     // Create the first page, as the sole child (for now) of the printed sheet
     // frame that we just created.

layout/style/nsCSSAnonBoxList.h

@@ -114,7 +114,6 @@ CSS_ANON_BOX(canvas, ":-moz-canvas")
 CSS_ANON_BOX(pageSequence, ":-moz-page-sequence")
 CSS_ANON_BOX(scrolledContent, ":-moz-scrolled-content")
 CSS_ANON_BOX(scrolledCanvas, ":-moz-scrolled-canvas")
-CSS_ANON_BOX(scrolledPageSequence, ":-moz-scrolled-page-sequence")
 
 // A column set is a set of columns inside of ColumnSetWrapperFrame, which
 // applies to nsColumnSetFrame. It doesn't contain any column-span elements.

layout/style/res/ua.css

@@ -200,8 +200,7 @@
   overflow-clip-box: inherit;
 }
 
-*|*::-moz-scrolled-content, *|*::-moz-scrolled-canvas,
+*|*::-moz-scrolled-content, *|*::-moz-scrolled-canvas {
-*|*::-moz-scrolled-page-sequence {
   /* e.g., text inputs, select boxes */
   padding: inherit;
   /* The display doesn't affect the kind of frame constructed here.  This just
@@ -291,7 +290,7 @@
   display: block;
 }
 
-*|*::-moz-page-sequence, *|*::-moz-scrolled-page-sequence {
+*|*::-moz-page-sequence {
   /* Collection of pages in print/print preview. Visual styles may only appear
    * in print preview. */
   display: block;

xpcom/ds/StaticAtoms.py

@@ -2476,7 +2476,6 @@ STATIC_ATOMS = [
     InheritingAnonBoxAtom("AnonBox_pageSequence", ":-moz-page-sequence"),
     InheritingAnonBoxAtom("AnonBox_scrolledContent", ":-moz-scrolled-content"),
     InheritingAnonBoxAtom("AnonBox_scrolledCanvas", ":-moz-scrolled-canvas"),
-    InheritingAnonBoxAtom("AnonBox_scrolledPageSequence", ":-moz-scrolled-page-sequence"),
     InheritingAnonBoxAtom("AnonBox_columnSet", ":-moz-column-set"),
     InheritingAnonBoxAtom("AnonBox_columnContent", ":-moz-column-content"),
     InheritingAnonBoxAtom("AnonBox_viewport", ":-moz-viewport"),