Add m-esr52 at 52.6.0

1 files changed, 3071 insertions, 0 deletions

diff --git a/layout/generic/ReflowInput.cpp b/layout/generic/ReflowInput.cpp
new file mode 100644
index 000000000..42f4a24b5
--- /dev/null
+++ b/layout/generic/ReflowInput.cpp
@@ -0,0 +1,3071 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* struct containing the input to nsIFrame::Reflow */
+
+#include "mozilla/ReflowInput.h"
+
+#include "LayoutLogging.h"
+#include "nsStyleConsts.h"
+#include "nsCSSAnonBoxes.h"
+#include "nsFrame.h"
+#include "nsIContent.h"
+#include "nsGkAtoms.h"
+#include "nsPresContext.h"
+#include "nsIPresShell.h"
+#include "nsFontMetrics.h"
+#include "nsBlockFrame.h"
+#include "nsLineBox.h"
+#include "nsImageFrame.h"
+#include "nsTableFrame.h"
+#include "nsTableCellFrame.h"
+#include "nsIPercentBSizeObserver.h"
+#include "nsLayoutUtils.h"
+#include "mozilla/Preferences.h"
+#include "nsFontInflationData.h"
+#include "StickyScrollContainer.h"
+#include "nsIFrameInlines.h"
+#include "CounterStyleManager.h"
+#include <algorithm>
+#include "mozilla/dom/HTMLInputElement.h"
+
+#ifdef DEBUG
+#undef NOISY_VERTICAL_ALIGN
+#else
+#undef NOISY_VERTICAL_ALIGN
+#endif
+
+using namespace mozilla;
+using namespace mozilla::css;
+using namespace mozilla::dom;
+using namespace mozilla::layout;
+
+enum eNormalLineHeightControl {
+  eUninitialized = -1,
+  eNoExternalLeading = 0,   // does not include external leading 
+  eIncludeExternalLeading,  // use whatever value font vendor provides
+  eCompensateLeading        // compensate leading if leading provided by font vendor is not enough
+};
+
+static eNormalLineHeightControl sNormalLineHeightControl = eUninitialized;
+
+// Initialize a <b>root</b> reflow state with a rendering context to
+// use for measuring things.
+ReflowInput::ReflowInput(nsPresContext*       aPresContext,
+                                     nsIFrame*            aFrame,
+                                     nsRenderingContext*  aRenderingContext,
+                                     const LogicalSize&   aAvailableSpace,
+                                     uint32_t             aFlags)
+  : SizeComputationInput(aFrame, aRenderingContext)
+  , mBlockDelta(0)
+  , mOrthogonalLimit(NS_UNCONSTRAINEDSIZE)
+  , mReflowDepth(0)
+{
+  NS_PRECONDITION(aRenderingContext, "no rendering context");
+  MOZ_ASSERT(aPresContext, "no pres context");
+  MOZ_ASSERT(aFrame, "no frame");
+  MOZ_ASSERT(aPresContext == aFrame->PresContext(), "wrong pres context");
+  mParentReflowInput = nullptr;
+  AvailableISize() = aAvailableSpace.ISize(mWritingMode);
+  AvailableBSize() = aAvailableSpace.BSize(mWritingMode);
+  mFloatManager = nullptr;
+  mLineLayout = nullptr;
+  mDiscoveredClearance = nullptr;
+  mPercentBSizeObserver = nullptr;
+
+  if (aFlags & DUMMY_PARENT_REFLOW_STATE) {
+    mFlags.mDummyParentReflowInput = true;
+  }
+  if (aFlags & COMPUTE_SIZE_SHRINK_WRAP) {
+    mFlags.mShrinkWrap = true;
+  }
+  if (aFlags & COMPUTE_SIZE_USE_AUTO_BSIZE) {
+    mFlags.mUseAutoBSize = true;
+  }
+  if (aFlags & STATIC_POS_IS_CB_ORIGIN) {
+    mFlags.mStaticPosIsCBOrigin = true;
+  }
+  if (aFlags & I_CLAMP_MARGIN_BOX_MIN_SIZE) {
+    mFlags.mIClampMarginBoxMinSize = true;
+  }
+  if (aFlags & B_CLAMP_MARGIN_BOX_MIN_SIZE) {
+    mFlags.mBClampMarginBoxMinSize = true;
+  }
+
+  if (!(aFlags & CALLER_WILL_INIT)) {
+    Init(aPresContext);
+  }
+}
+
+static bool CheckNextInFlowParenthood(nsIFrame* aFrame, nsIFrame* aParent)
+{
+  nsIFrame* frameNext = aFrame->GetNextInFlow();
+  nsIFrame* parentNext = aParent->GetNextInFlow();
+  return frameNext && parentNext && frameNext->GetParent() == parentNext;
+}
+
+/**
+ * Adjusts the margin for a list (ol, ul), if necessary, depending on
+ * font inflation settings. Unfortunately, because bullets from a list are
+ * placed in the margin area, we only have ~40px in which to place the
+ * bullets. When they are inflated, however, this causes problems, since
+ * the text takes up more space than is available in the margin.
+ *
+ * This method will return a small amount (in app units) by which the
+ * margin can be adjusted, so that the space is available for list
+ * bullets to be rendered with font inflation enabled.
+ */
+static  nscoord
+FontSizeInflationListMarginAdjustment(const nsIFrame* aFrame)
+{
+  float inflation = nsLayoutUtils::FontSizeInflationFor(aFrame);
+  if (aFrame->IsFrameOfType(nsIFrame::eBlockFrame)) {
+    const nsBlockFrame* blockFrame = static_cast<const nsBlockFrame*>(aFrame);
+
+    // We only want to adjust the margins if we're dealing with an ordered
+    // list.
+    if (inflation > 1.0f &&
+        blockFrame->HasBullet() &&
+        inflation > 1.0f) {
+
+      auto listStyleType = aFrame->StyleList()->GetCounterStyle()->GetStyle();
+      if (listStyleType != NS_STYLE_LIST_STYLE_NONE &&
+          listStyleType != NS_STYLE_LIST_STYLE_DISC &&
+          listStyleType != NS_STYLE_LIST_STYLE_CIRCLE &&
+          listStyleType != NS_STYLE_LIST_STYLE_SQUARE &&
+          listStyleType != NS_STYLE_LIST_STYLE_DISCLOSURE_CLOSED &&
+          listStyleType != NS_STYLE_LIST_STYLE_DISCLOSURE_OPEN) {
+        // The HTML spec states that the default padding for ordered lists
+        // begins at 40px, indicating that we have 40px of space to place a
+        // bullet. When performing font inflation calculations, we add space
+        // equivalent to this, but simply inflated at the same amount as the
+        // text, in app units.
+        return nsPresContext::CSSPixelsToAppUnits(40) * (inflation - 1);
+      }
+
+    }
+  }
+
+  return 0;
+}
+
+// NOTE: If we ever want to use SizeComputationInput for a flex item or a
+// grid item, we need to make it take the containing-block block-size as
+// well as the inline-size, since flex items and grid items resolve
+// block-direction percent margins and padding against the
+// containing-block block-size, rather than its inline-size.
+SizeComputationInput::SizeComputationInput(nsIFrame *aFrame,
+                                   nsRenderingContext *aRenderingContext,
+                                   WritingMode aContainingBlockWritingMode,
+                                   nscoord aContainingBlockISize)
+  : mFrame(aFrame)
+  , mRenderingContext(aRenderingContext)
+  , mWritingMode(aFrame->GetWritingMode())
+{
+  MOZ_ASSERT(!aFrame->IsFlexOrGridItem(),
+             "We're about to resolve percent margin & padding "
+             "values against CB inline size, which is incorrect for "
+             "flex/grid items. "
+             "Additionally for grid items, this path doesn't handle baseline "
+             "padding contribution - see SizeComputationInput::InitOffsets");
+  LogicalSize cbSize(aContainingBlockWritingMode, aContainingBlockISize,
+                     aContainingBlockISize);
+  ReflowInputFlags flags;
+  InitOffsets(aContainingBlockWritingMode, cbSize, mFrame->GetType(), flags);
+}
+
+// Initialize a reflow state for a child frame's reflow. Some state
+// is copied from the parent reflow state; the remaining state is
+// computed.
+ReflowInput::ReflowInput(
+                     nsPresContext*           aPresContext,
+                     const ReflowInput& aParentReflowInput,
+                     nsIFrame*                aFrame,
+                     const LogicalSize&       aAvailableSpace,
+                     const LogicalSize*       aContainingBlockSize,
+                     uint32_t                 aFlags)
+  : SizeComputationInput(aFrame, aParentReflowInput.mRenderingContext)
+  , mBlockDelta(0)
+  , mOrthogonalLimit(NS_UNCONSTRAINEDSIZE)
+  , mFlags(aParentReflowInput.mFlags)
+  , mReflowDepth(aParentReflowInput.mReflowDepth + 1)
+{
+  MOZ_ASSERT(aPresContext, "no pres context");
+  MOZ_ASSERT(aFrame, "no frame");
+  MOZ_ASSERT(aPresContext == aFrame->PresContext(), "wrong pres context");
+  NS_PRECONDITION(!mFlags.mSpecialBSizeReflow ||
+                  !NS_SUBTREE_DIRTY(aFrame),
+                  "frame should be clean when getting special bsize reflow");
+
+  mParentReflowInput = &aParentReflowInput;
+
+  // If the parent is dirty, then the child is as well.
+  // XXX Are the other cases where the parent reflows a child a second
+  // time, as a resize?
+  if (!mFlags.mSpecialBSizeReflow)
+    mFrame->AddStateBits(mParentReflowInput->mFrame->GetStateBits() &
+                        NS_FRAME_IS_DIRTY);
+
+  AvailableISize() = aAvailableSpace.ISize(mWritingMode);
+  AvailableBSize() = aAvailableSpace.BSize(mWritingMode);
+
+  if (mWritingMode.IsOrthogonalTo(aParentReflowInput.GetWritingMode())) {
+    // If we're setting up for an orthogonal flow, and the parent reflow state
+    // had a constrained ComputedBSize, we can use that as our AvailableISize
+    // in preference to leaving it unconstrained.
+    if (AvailableISize() == NS_UNCONSTRAINEDSIZE &&
+        aParentReflowInput.ComputedBSize() != NS_UNCONSTRAINEDSIZE) {
+      AvailableISize() = aParentReflowInput.ComputedBSize();
+    }
+  }
+
+  mFloatManager = aParentReflowInput.mFloatManager;
+  if (mFrame->IsFrameOfType(nsIFrame::eLineParticipant))
+    mLineLayout = aParentReflowInput.mLineLayout;
+  else
+    mLineLayout = nullptr;
+
+  // Note: mFlags was initialized as a copy of aParentReflowInput.mFlags up in
+  // this constructor's init list, so the only flags that we need to explicitly
+  // initialize here are those that may need a value other than our parent's.
+  mFlags.mNextInFlowUntouched = aParentReflowInput.mFlags.mNextInFlowUntouched &&
+    CheckNextInFlowParenthood(aFrame, aParentReflowInput.mFrame);
+  mFlags.mAssumingHScrollbar = mFlags.mAssumingVScrollbar = false;
+  mFlags.mIsColumnBalancing = false;
+  mFlags.mIsFlexContainerMeasuringHeight = false;
+  mFlags.mDummyParentReflowInput = false;
+  mFlags.mShrinkWrap = !!(aFlags & COMPUTE_SIZE_SHRINK_WRAP);
+  mFlags.mUseAutoBSize = !!(aFlags & COMPUTE_SIZE_USE_AUTO_BSIZE);
+  mFlags.mStaticPosIsCBOrigin = !!(aFlags & STATIC_POS_IS_CB_ORIGIN);
+  mFlags.mIOffsetsNeedCSSAlign = mFlags.mBOffsetsNeedCSSAlign = false;
+  mFlags.mIClampMarginBoxMinSize = !!(aFlags & I_CLAMP_MARGIN_BOX_MIN_SIZE);
+  mFlags.mBClampMarginBoxMinSize = !!(aFlags & B_CLAMP_MARGIN_BOX_MIN_SIZE);
+
+  mDiscoveredClearance = nullptr;
+  mPercentBSizeObserver = (aParentReflowInput.mPercentBSizeObserver &&
+                            aParentReflowInput.mPercentBSizeObserver->NeedsToObserve(*this))
+                           ? aParentReflowInput.mPercentBSizeObserver : nullptr;
+
+  if ((aFlags & DUMMY_PARENT_REFLOW_STATE) ||
+      (mParentReflowInput->mFlags.mDummyParentReflowInput &&
+       mFrame->GetType() == nsGkAtoms::tableFrame)) {
+    mFlags.mDummyParentReflowInput = true;
+  }
+
+  if (!(aFlags & CALLER_WILL_INIT)) {
+    Init(aPresContext, aContainingBlockSize);
+  }
+}
+
+inline nscoord
+SizeComputationInput::ComputeISizeValue(nscoord aContainingBlockISize,
+                                    nscoord aContentEdgeToBoxSizing,
+                                    nscoord aBoxSizingToMarginEdge,
+                                    const nsStyleCoord& aCoord) const
+{
+  return mFrame->ComputeISizeValue(mRenderingContext,
+                                   aContainingBlockISize,
+                                   aContentEdgeToBoxSizing,
+                                   aBoxSizingToMarginEdge,
+                                   aCoord);
+}
+
+nscoord
+SizeComputationInput::ComputeISizeValue(nscoord aContainingBlockISize,
+                                    StyleBoxSizing aBoxSizing,
+                                    const nsStyleCoord& aCoord) const
+{
+  WritingMode wm = GetWritingMode();
+  nscoord inside = 0, outside = ComputedLogicalBorderPadding().IStartEnd(wm) +
+                                ComputedLogicalMargin().IStartEnd(wm);
+  if (aBoxSizing == StyleBoxSizing::Border) {
+    inside = ComputedLogicalBorderPadding().IStartEnd(wm);
+  }
+  outside -= inside;
+
+  return ComputeISizeValue(aContainingBlockISize, inside,
+                           outside, aCoord);
+}
+
+nscoord
+SizeComputationInput::ComputeBSizeValue(nscoord aContainingBlockBSize,
+                                    StyleBoxSizing aBoxSizing,
+                                    const nsStyleCoord& aCoord) const
+{
+  WritingMode wm = GetWritingMode();
+  nscoord inside = 0;
+  if (aBoxSizing == StyleBoxSizing::Border) {
+    inside = ComputedLogicalBorderPadding().BStartEnd(wm);
+  }
+  return nsLayoutUtils::ComputeBSizeValue(aContainingBlockBSize,
+                                          inside, aCoord);
+}
+
+void
+ReflowInput::SetComputedWidth(nscoord aComputedWidth)
+{
+  NS_ASSERTION(mFrame, "Must have a frame!");
+  // It'd be nice to assert that |frame| is not in reflow, but this fails for
+  // two reasons:
+  //
+  // 1) Viewport frames reset the computed width on a copy of their reflow
+  //    state when reflowing fixed-pos kids.  In that case we actually don't
+  //    want to mess with the resize flags, because comparing the frame's rect
+  //    to the munged computed width is pointless.
+  // 2) nsFrame::BoxReflow creates a reflow state for its parent.  This reflow
+  //    state is not used to reflow the parent, but just as a parent for the
+  //    frame's own reflow state.  So given a nsBoxFrame inside some non-XUL
+  //    (like a text control, for example), we'll end up creating a reflow
+  //    state for the parent while the parent is reflowing.
+
+  NS_PRECONDITION(aComputedWidth >= 0, "Invalid computed width");
+  if (ComputedWidth() != aComputedWidth) {
+    ComputedWidth() = aComputedWidth;
+    nsIAtom* frameType = mFrame->GetType();
+    if (frameType != nsGkAtoms::viewportFrame || // Or check GetParent()?
+        mWritingMode.IsVertical()) {
+      InitResizeFlags(mFrame->PresContext(), frameType);
+    }
+  }
+}
+
+void
+ReflowInput::SetComputedHeight(nscoord aComputedHeight)
+{
+  NS_ASSERTION(mFrame, "Must have a frame!");
+  // It'd be nice to assert that |frame| is not in reflow, but this fails
+  // because:
+  //
+  //    nsFrame::BoxReflow creates a reflow state for its parent.  This reflow
+  //    state is not used to reflow the parent, but just as a parent for the
+  //    frame's own reflow state.  So given a nsBoxFrame inside some non-XUL
+  //    (like a text control, for example), we'll end up creating a reflow
+  //    state for the parent while the parent is reflowing.
+
+  NS_PRECONDITION(aComputedHeight >= 0, "Invalid computed height");
+  if (ComputedHeight() != aComputedHeight) {
+    ComputedHeight() = aComputedHeight;
+    nsIAtom* frameType = mFrame->GetType();
+    if (frameType != nsGkAtoms::viewportFrame || !mWritingMode.IsVertical()) {
+      InitResizeFlags(mFrame->PresContext(), frameType);
+    }
+  }
+}
+
+void
+ReflowInput::Init(nsPresContext*     aPresContext,
+                        const LogicalSize* aContainingBlockSize,
+                        const nsMargin*    aBorder,
+                        const nsMargin*    aPadding)
+{
+  if (AvailableISize() == NS_UNCONSTRAINEDSIZE) {
+    // Look up the parent chain for an orthogonal inline limit,
+    // and reset AvailableISize() if found.
+    for (const ReflowInput *parent = mParentReflowInput;
+         parent != nullptr; parent = parent->mParentReflowInput) {
+      if (parent->GetWritingMode().IsOrthogonalTo(mWritingMode) &&
+          parent->mOrthogonalLimit != NS_UNCONSTRAINEDSIZE) {
+        AvailableISize() = parent->mOrthogonalLimit;
+        break;
+      }
+    }
+  }
+
+  LAYOUT_WARN_IF_FALSE(AvailableISize() != NS_UNCONSTRAINEDSIZE,
+                       "have unconstrained inline-size; this should only "
+                       "result from very large sizes, not attempts at "
+                       "intrinsic inline-size calculation");
+
+  mStylePosition = mFrame->StylePosition();
+  mStyleDisplay = mFrame->StyleDisplay();
+  mStyleVisibility = mFrame->StyleVisibility();
+  mStyleBorder = mFrame->StyleBorder();
+  mStyleMargin = mFrame->StyleMargin();
+  mStylePadding = mFrame->StylePadding();
+  mStyleText = mFrame->StyleText();
+
+  nsIAtom* type = mFrame->GetType();
+
+  InitFrameType(type);
+  InitCBReflowInput();
+
+  LogicalSize cbSize(mWritingMode, -1, -1);
+  if (aContainingBlockSize) {
+    cbSize = *aContainingBlockSize;
+  }
+
+  InitConstraints(aPresContext, cbSize, aBorder, aPadding, type);
+
+  InitResizeFlags(aPresContext, type);
+
+  nsIFrame *parent = mFrame->GetParent();
+  if (parent &&
+      (parent->GetStateBits() & NS_FRAME_IN_CONSTRAINED_BSIZE) &&
+      !(parent->GetType() == nsGkAtoms::scrollFrame &&
+        parent->StyleDisplay()->mOverflowY != NS_STYLE_OVERFLOW_HIDDEN)) {
+    mFrame->AddStateBits(NS_FRAME_IN_CONSTRAINED_BSIZE);
+  } else if (type == nsGkAtoms::svgForeignObjectFrame) {
+    // An SVG foreignObject frame is inherently constrained block-size.
+    mFrame->AddStateBits(NS_FRAME_IN_CONSTRAINED_BSIZE);
+  } else {
+    const nsStyleCoord& bSizeCoord = mStylePosition->BSize(mWritingMode);
+    const nsStyleCoord& maxBSizeCoord = mStylePosition->MaxBSize(mWritingMode);
+    if ((bSizeCoord.GetUnit() != eStyleUnit_Auto ||
+         maxBSizeCoord.GetUnit() != eStyleUnit_None) &&
+         // Don't set NS_FRAME_IN_CONSTRAINED_BSIZE on body or html elements.
+         (mFrame->GetContent() &&
+        !(mFrame->GetContent()->IsAnyOfHTMLElements(nsGkAtoms::body,
+                                                   nsGkAtoms::html)))) {
+
+      // If our block-size was specified as a percentage, then this could
+      // actually resolve to 'auto', based on:
+      // http://www.w3.org/TR/CSS21/visudet.html#the-height-property
+      nsIFrame* containingBlk = mFrame;
+      while (containingBlk) {
+        const nsStylePosition* stylePos = containingBlk->StylePosition();
+        const nsStyleCoord& bSizeCoord = stylePos->BSize(mWritingMode);
+        const nsStyleCoord& maxBSizeCoord = stylePos->MaxBSize(mWritingMode);
+        if ((bSizeCoord.IsCoordPercentCalcUnit() &&
+             !bSizeCoord.HasPercent()) ||
+            (maxBSizeCoord.IsCoordPercentCalcUnit() &&
+             !maxBSizeCoord.HasPercent())) {
+          mFrame->AddStateBits(NS_FRAME_IN_CONSTRAINED_BSIZE);
+          break;
+        } else if ((bSizeCoord.IsCoordPercentCalcUnit() &&
+                    bSizeCoord.HasPercent()) ||
+                   (maxBSizeCoord.IsCoordPercentCalcUnit() &&
+                    maxBSizeCoord.HasPercent())) {
+          if (!(containingBlk = containingBlk->GetContainingBlock())) {
+            // If we've reached the top of the tree, then we don't have
+            // a constrained block-size.
+            mFrame->RemoveStateBits(NS_FRAME_IN_CONSTRAINED_BSIZE);
+            break;
+          }
+
+          continue;
+        } else {
+          mFrame->RemoveStateBits(NS_FRAME_IN_CONSTRAINED_BSIZE);
+          break;
+        }
+      }
+    } else {
+      mFrame->RemoveStateBits(NS_FRAME_IN_CONSTRAINED_BSIZE);
+    }
+  }
+
+  if (mParentReflowInput &&
+      mParentReflowInput->GetWritingMode().IsOrthogonalTo(mWritingMode)) {
+    // Orthogonal frames are always reflowed with an unconstrained
+    // dimension to avoid incomplete reflow across an orthogonal
+    // boundary. Normally this is the block-size, but for column sets
+    // with auto-height it's the inline-size, so that they can add
+    // columns in the container's block direction
+    if (type == nsGkAtoms::columnSetFrame &&
+        eStyleUnit_Auto == mStylePosition->ISize(mWritingMode).GetUnit()) {
+      ComputedISize() = NS_UNCONSTRAINEDSIZE;
+    } else {
+      AvailableBSize() = NS_UNCONSTRAINEDSIZE;
+    }
+  }
+
+  LAYOUT_WARN_IF_FALSE((mFrameType == NS_CSS_FRAME_TYPE_INLINE &&
+                        !mFrame->IsFrameOfType(nsIFrame::eReplaced)) ||
+                       type == nsGkAtoms::textFrame ||
+                       ComputedISize() != NS_UNCONSTRAINEDSIZE,
+                       "have unconstrained inline-size; this should only "
+                       "result from very large sizes, not attempts at "
+                       "intrinsic inline-size calculation");
+}
+
+void ReflowInput::InitCBReflowInput()
+{
+  if (!mParentReflowInput) {
+    mCBReflowInput = nullptr;
+    return;
+  }
+  if (mParentReflowInput->mFlags.mDummyParentReflowInput) {
+    mCBReflowInput = mParentReflowInput;
+    return;
+  }
+
+  if (mParentReflowInput->mFrame == mFrame->GetContainingBlock()) {
+    // Inner table frames need to use the containing block of the outer
+    // table frame.
+    if (mFrame->GetType() == nsGkAtoms::tableFrame) {
+      mCBReflowInput = mParentReflowInput->mCBReflowInput;
+    } else {
+      mCBReflowInput = mParentReflowInput;
+    }
+  } else {
+    mCBReflowInput = mParentReflowInput->mCBReflowInput;
+  }
+}
+
+/* Check whether CalcQuirkContainingBlockHeight would stop on the
+ * given reflow state, using its block as a height.  (essentially 
+ * returns false for any case in which CalcQuirkContainingBlockHeight 
+ * has a "continue" in its main loop.)
+ *
+ * XXX Maybe refactor CalcQuirkContainingBlockHeight so it uses 
+ * this function as well
+ */
+static bool
+IsQuirkContainingBlockHeight(const ReflowInput* rs, nsIAtom* aFrameType)
+{
+  if (nsGkAtoms::blockFrame == aFrameType ||
+#ifdef MOZ_XUL
+      nsGkAtoms::XULLabelFrame == aFrameType ||
+#endif
+      nsGkAtoms::scrollFrame == aFrameType) {
+    // Note: This next condition could change due to a style change,
+    // but that would cause a style reflow anyway, which means we're ok.
+    if (NS_AUTOHEIGHT == rs->ComputedHeight()) {
+      if (!rs->mFrame->IsAbsolutelyPositioned()) {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
+
+void
+ReflowInput::InitResizeFlags(nsPresContext* aPresContext, nsIAtom* aFrameType)
+{
+  const WritingMode wm = mWritingMode; // just a shorthand
+  // We should report that we have a resize in the inline dimension if
+  // *either* the border-box size or the content-box size in that
+  // dimension has changed.  It might not actually be necessary to do
+  // this if the border-box size has changed and the content-box size
+  // has not changed, but since we've historically used the flag to mean
+  // border-box size change, continue to do that.  (It's possible for
+  // the content-box size to change without a border-box size change or
+  // a style change given (1) a fixed width (possibly fixed by max-width
+  // or min-width), (2) box-sizing:border-box or padding-box, and
+  // (3) percentage padding.)
+  //
+  // However, we don't actually have the information at this point to
+  // tell whether the content-box size has changed, since both style
+  // data and the UsedPaddingProperty() have already been updated.  So,
+  // instead, we explicitly check for the case where it's possible for
+  // the content-box size to have changed without either (a) a change in
+  // the border-box size or (b) an nsChangeHint_NeedDirtyReflow change
+  // hint due to change in border or padding.  Thus we test using the
+  // conditions from the previous paragraph, except without testing (1)
+  // since it's complicated to test properly and less likely to help
+  // with optimizing cases away.
+  bool isIResize =
+    // is the border-box resizing?
+    mFrame->ISize(wm) !=
+      ComputedISize() + ComputedLogicalBorderPadding().IStartEnd(wm) ||
+    // or is the content-box resizing?  (see comment above)
+    (mStylePosition->mBoxSizing != StyleBoxSizing::Content &&
+     mStylePadding->IsWidthDependent());
+
+  if ((mFrame->GetStateBits() & NS_FRAME_FONT_INFLATION_FLOW_ROOT) &&
+      nsLayoutUtils::FontSizeInflationEnabled(aPresContext)) {
+    // Create our font inflation data if we don't have it already, and
+    // give it our current width information.
+    bool dirty = nsFontInflationData::UpdateFontInflationDataISizeFor(*this) &&
+                 // Avoid running this at the box-to-block interface
+                 // (where we shouldn't be inflating anyway, and where
+                 // reflow state construction is probably to construct a
+                 // dummy parent reflow state anyway).
+                 !mFlags.mDummyParentReflowInput;
+
+    if (dirty || (!mFrame->GetParent() && isIResize)) {
+      // When font size inflation is enabled, a change in either:
+      //  * the effective width of a font inflation flow root
+      //  * the width of the frame
+      // needs to cause a dirty reflow since they change the font size
+      // inflation calculations, which in turn change the size of text,
+      // line-heights, etc.  This is relatively similar to a classic
+      // case of style change reflow, except that because inflation
+      // doesn't affect the intrinsic sizing codepath, there's no need
+      // to invalidate intrinsic sizes.
+      //
+      // Note that this makes horizontal resizing a good bit more
+      // expensive.  However, font size inflation is targeted at a set of
+      // devices (zoom-and-pan devices) where the main use case for
+      // horizontal resizing needing to be efficient (window resizing) is
+      // not present.  It does still increase the cost of dynamic changes
+      // caused by script where a style or content change in one place
+      // causes a resize in another (e.g., rebalancing a table).
+
+      // FIXME: This isn't so great for the cases where
+      // ReflowInput::SetComputedWidth is called, if the first time
+      // we go through InitResizeFlags we set IsHResize() to true, and then
+      // the second time we'd set it to false even without the
+      // NS_FRAME_IS_DIRTY bit already set.
+      if (mFrame->GetType() == nsGkAtoms::svgForeignObjectFrame) {
+        // Foreign object frames use dirty bits in a special way.
+        mFrame->AddStateBits(NS_FRAME_HAS_DIRTY_CHILDREN);
+        nsIFrame *kid = mFrame->PrincipalChildList().FirstChild();
+        if (kid) {
+          kid->AddStateBits(NS_FRAME_IS_DIRTY);
+        }
+      } else {
+        mFrame->AddStateBits(NS_FRAME_IS_DIRTY);
+      }
+
+      // Mark intrinsic widths on all descendants dirty.  We need to do
+      // this (1) since we're changing the size of text and need to
+      // clear text runs on text frames and (2) since we actually are
+      // changing some intrinsic widths, but only those that live inside
+      // of containers.
+
+      // It makes sense to do this for descendants but not ancestors
+      // (which is unusual) because we're only changing the unusual
+      // inflation-dependent intrinsic widths (i.e., ones computed with
+      // nsPresContext::mInflationDisabledForShrinkWrap set to false),
+      // which should never affect anything outside of their inflation
+      // flow root (or, for that matter, even their inflation
+      // container).
+
+      // This is also different from what PresShell::FrameNeedsReflow
+      // does because it doesn't go through placeholders.  It doesn't
+      // need to because we're actually doing something that cares about
+      // frame tree geometry (the width on an ancestor) rather than
+      // style.
+
+      AutoTArray<nsIFrame*, 32> stack;
+      stack.AppendElement(mFrame);
+
+      do {
+        nsIFrame *f = stack.ElementAt(stack.Length() - 1);
+        stack.RemoveElementAt(stack.Length() - 1);
+
+        nsIFrame::ChildListIterator lists(f);
+        for (; !lists.IsDone(); lists.Next()) {
+          nsFrameList::Enumerator childFrames(lists.CurrentList());
+          for (; !childFrames.AtEnd(); childFrames.Next()) {
+            nsIFrame* kid = childFrames.get();
+            kid->MarkIntrinsicISizesDirty();
+            stack.AppendElement(kid);
+          }
+        }
+      } while (stack.Length() != 0);
+    }
+  }
+
+  SetIResize(!(mFrame->GetStateBits() & NS_FRAME_IS_DIRTY) &&
+             isIResize);
+
+  // XXX Should we really need to null check mCBReflowInput?  (We do for
+  // at least nsBoxFrame).
+  if (IS_TABLE_CELL(aFrameType) &&
+      (mFlags.mSpecialBSizeReflow ||
+       (mFrame->FirstInFlow()->GetStateBits() &
+         NS_TABLE_CELL_HAD_SPECIAL_REFLOW)) &&
+      (mFrame->GetStateBits() & NS_FRAME_CONTAINS_RELATIVE_BSIZE)) {
+    // Need to set the bit on the cell so that
+    // mCBReflowInput->IsBResize() is set correctly below when
+    // reflowing descendant.
+    SetBResize(true);
+  } else if (mCBReflowInput && mFrame->IsBlockWrapper()) {
+    // XXX Is this problematic for relatively positioned inlines acting
+    // as containing block for absolutely positioned elements?
+    // Possibly; in that case we should at least be checking
+    // NS_SUBTREE_DIRTY, I'd think.
+    SetBResize(mCBReflowInput->IsBResizeForWM(wm));
+  } else if (mCBReflowInput && !nsLayoutUtils::GetAsBlock(mFrame)) {
+    // Some non-block frames (e.g. table frames) aggressively optimize out their
+    // BSize recomputation when they don't have the BResize flag set.  This
+    // means that if they go from having a computed non-auto height to having an
+    // auto height and don't have that flag set, they will not actually compute
+    // their auto height and will just remain at whatever size they already
+    // were.  We can end up in that situation if the child has a percentage
+    // specified height and the parent changes from non-auto height to auto
+    // height.  When that happens, the parent will typically have the BResize
+    // flag set, and we want to propagate that flag to the kid.
+    //
+    // Ideally it seems like we'd do this for blocks too, of course... but we'd
+    // really want to restrict it to the percentage height case or something, to
+    // avoid extra reflows in common cases.  Maybe we should be examining
+    // mStylePosition->BSize(wm).GetUnit() for that purpose?
+    //
+    // Note that we _also_ need to set the BResize flag if we have auto
+    // ComputedBSize() and a dirty subtree, since that might require us to
+    // change BSize due to kids having been added or removed.
+    SetBResize(mCBReflowInput->IsBResizeForWM(wm));
+    if (ComputedBSize() == NS_AUTOHEIGHT) {
+      SetBResize(IsBResize() || NS_SUBTREE_DIRTY(mFrame));
+    }
+  } else if (ComputedBSize() == NS_AUTOHEIGHT) {
+    if (eCompatibility_NavQuirks == aPresContext->CompatibilityMode() &&
+        mCBReflowInput) {
+      SetBResize(mCBReflowInput->IsBResizeForWM(wm));
+    } else {
+      SetBResize(IsIResize());
+    }
+    SetBResize(IsBResize() || NS_SUBTREE_DIRTY(mFrame));
+  } else {
+    // not 'auto' block-size
+    SetBResize(mFrame->BSize(wm) !=
+               ComputedBSize() + ComputedLogicalBorderPadding().BStartEnd(wm));
+  }
+
+  bool dependsOnCBBSize =
+    (mStylePosition->BSizeDependsOnContainer(wm) &&
+     // FIXME: condition this on not-abspos?
+     mStylePosition->BSize(wm).GetUnit() != eStyleUnit_Auto) ||
+    mStylePosition->MinBSizeDependsOnContainer(wm) ||
+    mStylePosition->MaxBSizeDependsOnContainer(wm) ||
+    mStylePosition->OffsetHasPercent(wm.PhysicalSide(eLogicalSideBStart)) ||
+    mStylePosition->mOffset.GetBEndUnit(wm) != eStyleUnit_Auto ||
+    mFrame->IsXULBoxFrame();
+
+  if (mStyleText->mLineHeight.GetUnit() == eStyleUnit_Enumerated) {
+    NS_ASSERTION(mStyleText->mLineHeight.GetIntValue() ==
+                 NS_STYLE_LINE_HEIGHT_BLOCK_HEIGHT,
+                 "bad line-height value");
+
+    // line-height depends on block bsize
+    mFrame->AddStateBits(NS_FRAME_CONTAINS_RELATIVE_BSIZE);
+    // but only on containing blocks if this frame is not a suitable block
+    dependsOnCBBSize |= !nsLayoutUtils::IsNonWrapperBlock(mFrame);
+  }
+
+  // If we're the descendant of a table cell that performs special bsize
+  // reflows and we could be the child that requires them, always set
+  // the block-axis resize in case this is the first pass before the
+  // special bsize reflow.  However, don't do this if it actually is
+  // the special bsize reflow, since in that case it will already be
+  // set correctly above if we need it set.
+  if (!IsBResize() && mCBReflowInput &&
+      (IS_TABLE_CELL(mCBReflowInput->mFrame->GetType()) || 
+       mCBReflowInput->mFlags.mHeightDependsOnAncestorCell) &&
+      !mCBReflowInput->mFlags.mSpecialBSizeReflow && 
+      dependsOnCBBSize) {
+    SetBResize(true);
+    mFlags.mHeightDependsOnAncestorCell = true;
+  }
+
+  // Set NS_FRAME_CONTAINS_RELATIVE_BSIZE if it's needed.
+
+  // It would be nice to check that |ComputedBSize != NS_AUTOHEIGHT|
+  // &&ed with the percentage bsize check.  However, this doesn't get
+  // along with table special bsize reflows, since a special bsize
+  // reflow (a quirk that makes such percentage height work on children
+  // of table cells) can cause not just a single percentage height to
+  // become fixed, but an entire descendant chain of percentage height
+  // to become fixed.
+  if (dependsOnCBBSize && mCBReflowInput) {
+    const ReflowInput *rs = this;
+    bool hitCBReflowInput = false;
+    do {
+      rs = rs->mParentReflowInput;
+      if (!rs) {
+        break;
+      }
+        
+      if (rs->mFrame->GetStateBits() & NS_FRAME_CONTAINS_RELATIVE_BSIZE)
+        break; // no need to go further
+      rs->mFrame->AddStateBits(NS_FRAME_CONTAINS_RELATIVE_BSIZE);
+      
+      // Keep track of whether we've hit the containing block, because
+      // we need to go at least that far.
+      if (rs == mCBReflowInput) {
+        hitCBReflowInput = true;
+      }
+
+      // XXX What about orthogonal flows? It doesn't make sense to
+      // keep propagating this bit across an orthogonal boundary,
+      // where the meaning of BSize changes. Bug 1175517.
+    } while (!hitCBReflowInput ||
+             (eCompatibility_NavQuirks == aPresContext->CompatibilityMode() &&
+              !IsQuirkContainingBlockHeight(rs, rs->mFrame->GetType())));
+    // Note: We actually don't need to set the
+    // NS_FRAME_CONTAINS_RELATIVE_BSIZE bit for the cases
+    // where we hit the early break statements in
+    // CalcQuirkContainingBlockHeight. But it doesn't hurt
+    // us to set the bit in these cases.
+    
+  }
+  if (mFrame->GetStateBits() & NS_FRAME_IS_DIRTY) {
+    // If we're reflowing everything, then we'll find out if we need
+    // to re-set this.
+    mFrame->RemoveStateBits(NS_FRAME_CONTAINS_RELATIVE_BSIZE);
+  }
+}
+
+nscoord
+ReflowInput::GetContainingBlockContentISize(WritingMode aWritingMode) const
+{
+  if (!mCBReflowInput) {
+    return 0;
+  }
+  return mCBReflowInput->GetWritingMode().IsOrthogonalTo(aWritingMode)
+    ? mCBReflowInput->ComputedBSize()
+    : mCBReflowInput->ComputedISize();
+}
+
+void
+ReflowInput::InitFrameType(nsIAtom* aFrameType)
+{
+  const nsStyleDisplay *disp = mStyleDisplay;
+  nsCSSFrameType frameType;
+
+  // Section 9.7 of the CSS2 spec indicates that absolute position
+  // takes precedence over float which takes precedence over display.
+  // XXXldb nsRuleNode::ComputeDisplayData should take care of this, right?
+  // Make sure the frame was actually moved out of the flow, and don't
+  // just assume what the style says, because we might not have had a
+  // useful float/absolute containing block
+
+  DISPLAY_INIT_TYPE(mFrame, this);
+
+  if (aFrameType == nsGkAtoms::tableFrame) {
+    mFrameType = NS_CSS_FRAME_TYPE_BLOCK;
+    return;
+  }
+
+  NS_ASSERTION(mFrame->StyleDisplay()->IsAbsolutelyPositionedStyle() ==
+                 disp->IsAbsolutelyPositionedStyle(),
+               "Unexpected position style");
+  NS_ASSERTION(mFrame->StyleDisplay()->IsFloatingStyle() ==
+                 disp->IsFloatingStyle(), "Unexpected float style");
+  if (mFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW) {
+    if (disp->IsAbsolutelyPositioned(mFrame)) {
+      frameType = NS_CSS_FRAME_TYPE_ABSOLUTE;
+      //XXXfr hack for making frames behave properly when in overflow container lists
+      //      see bug 154892; need to revisit later
+      if (mFrame->GetPrevInFlow())
+        frameType = NS_CSS_FRAME_TYPE_BLOCK;
+    }
+    else if (disp->IsFloating(mFrame)) {
+      frameType = NS_CSS_FRAME_TYPE_FLOATING;
+    } else {
+      NS_ASSERTION(disp->mDisplay == StyleDisplay::Popup,
+                   "unknown out of flow frame type");
+      frameType = NS_CSS_FRAME_TYPE_UNKNOWN;
+    }
+  }
+  else {
+    switch (GetDisplay()) {
+    case StyleDisplay::Block:
+    case StyleDisplay::ListItem:
+    case StyleDisplay::Table:
+    case StyleDisplay::TableCaption:
+    case StyleDisplay::Flex:
+    case StyleDisplay::WebkitBox:
+    case StyleDisplay::Grid:
+    case StyleDisplay::RubyTextContainer:
+      frameType = NS_CSS_FRAME_TYPE_BLOCK;
+      break;
+
+    case StyleDisplay::Inline:
+    case StyleDisplay::InlineBlock:
+    case StyleDisplay::InlineTable:
+    case StyleDisplay::InlineBox:
+    case StyleDisplay::InlineXulGrid:
+    case StyleDisplay::InlineStack:
+    case StyleDisplay::InlineFlex:
+    case StyleDisplay::WebkitInlineBox:
+    case StyleDisplay::InlineGrid:
+    case StyleDisplay::Ruby:
+    case StyleDisplay::RubyBase:
+    case StyleDisplay::RubyText:
+    case StyleDisplay::RubyBaseContainer:
+      frameType = NS_CSS_FRAME_TYPE_INLINE;
+      break;
+
+    case StyleDisplay::TableCell:
+    case StyleDisplay::TableRowGroup:
+    case StyleDisplay::TableColumn:
+    case StyleDisplay::TableColumnGroup:
+    case StyleDisplay::TableHeaderGroup:
+    case StyleDisplay::TableFooterGroup:
+    case StyleDisplay::TableRow:
+      frameType = NS_CSS_FRAME_TYPE_INTERNAL_TABLE;
+      break;
+
+    case StyleDisplay::None:
+    default:
+      frameType = NS_CSS_FRAME_TYPE_UNKNOWN;
+      break;
+    }
+  }
+
+  // See if the frame is replaced
+  if (mFrame->IsFrameOfType(nsIFrame::eReplacedContainsBlock)) {
+    frameType = NS_FRAME_REPLACED_CONTAINS_BLOCK(frameType);
+  } else if (mFrame->IsFrameOfType(nsIFrame::eReplaced)) {
+    frameType = NS_FRAME_REPLACED(frameType);
+  }
+
+  mFrameType = frameType;
+}
+
+/* static */ void
+ReflowInput::ComputeRelativeOffsets(WritingMode aWM,
+                                          nsIFrame* aFrame,
+                                          const LogicalSize& aCBSize,
+                                          nsMargin& aComputedOffsets)
+{
+  LogicalMargin offsets(aWM);
+  mozilla::css::Side inlineStart = aWM.PhysicalSide(eLogicalSideIStart);
+  mozilla::css::Side inlineEnd   = aWM.PhysicalSide(eLogicalSideIEnd);
+  mozilla::css::Side blockStart  = aWM.PhysicalSide(eLogicalSideBStart);
+  mozilla::css::Side blockEnd    = aWM.PhysicalSide(eLogicalSideBEnd);
+
+  const nsStylePosition* position = aFrame->StylePosition();
+
+  // Compute the 'inlineStart' and 'inlineEnd' values. 'inlineStart'
+  // moves the boxes to the end of the line, and 'inlineEnd' moves the
+  // boxes to the start of the line. The computed values are always:
+  // inlineStart=-inlineEnd
+  bool inlineStartIsAuto =
+    eStyleUnit_Auto == position->mOffset.GetUnit(inlineStart);
+  bool inlineEndIsAuto =
+    eStyleUnit_Auto == position->mOffset.GetUnit(inlineEnd);
+
+  // If neither 'inlineStart' nor 'inlineEnd' is auto, then we're
+  // over-constrained and we ignore one of them
+  if (!inlineStartIsAuto && !inlineEndIsAuto) {
+    inlineEndIsAuto = true;
+  }
+
+  if (inlineStartIsAuto) {
+    if (inlineEndIsAuto) {
+      // If both are 'auto' (their initial values), the computed values are 0
+      offsets.IStart(aWM) = offsets.IEnd(aWM) = 0;
+    } else {
+      // 'inlineEnd' isn't 'auto' so compute its value
+      offsets.IEnd(aWM) = nsLayoutUtils::
+        ComputeCBDependentValue(aCBSize.ISize(aWM),
+                                position->mOffset.Get(inlineEnd));
+
+      // Computed value for 'inlineStart' is minus the value of 'inlineEnd'
+      offsets.IStart(aWM) = -offsets.IEnd(aWM);
+    }
+
+  } else {
+    NS_ASSERTION(inlineEndIsAuto, "unexpected specified constraint");
+
+    // 'InlineStart' isn't 'auto' so compute its value
+    offsets.IStart(aWM) = nsLayoutUtils::
+      ComputeCBDependentValue(aCBSize.ISize(aWM),
+                              position->mOffset.Get(inlineStart));
+
+    // Computed value for 'inlineEnd' is minus the value of 'inlineStart'
+    offsets.IEnd(aWM) = -offsets.IStart(aWM);
+  }
+
+  // Compute the 'blockStart' and 'blockEnd' values. The 'blockStart'
+  // and 'blockEnd' properties move relatively positioned elements in
+  // the block progression direction. They also must be each other's
+  // negative
+  bool blockStartIsAuto =
+    eStyleUnit_Auto == position->mOffset.GetUnit(blockStart);
+  bool blockEndIsAuto =
+    eStyleUnit_Auto == position->mOffset.GetUnit(blockEnd);
+
+  // Check for percentage based values and a containing block block-size
+  // that depends on the content block-size. Treat them like 'auto'
+  if (NS_AUTOHEIGHT == aCBSize.BSize(aWM)) {
+    if (position->OffsetHasPercent(blockStart)) {
+      blockStartIsAuto = true;
+    }
+    if (position->OffsetHasPercent(blockEnd)) {
+      blockEndIsAuto = true;
+    }
+  }
+
+  // If neither is 'auto', 'block-end' is ignored
+  if (!blockStartIsAuto && !blockEndIsAuto) {
+    blockEndIsAuto = true;
+  }
+
+  if (blockStartIsAuto) {
+    if (blockEndIsAuto) {
+      // If both are 'auto' (their initial values), the computed values are 0
+      offsets.BStart(aWM) = offsets.BEnd(aWM) = 0;
+    } else {
+      // 'blockEnd' isn't 'auto' so compute its value
+      offsets.BEnd(aWM) = nsLayoutUtils::
+        ComputeBSizeDependentValue(aCBSize.BSize(aWM),
+                                   position->mOffset.Get(blockEnd));
+
+      // Computed value for 'blockStart' is minus the value of 'blockEnd'
+      offsets.BStart(aWM) = -offsets.BEnd(aWM);
+    }
+
+  } else {
+    NS_ASSERTION(blockEndIsAuto, "unexpected specified constraint");
+
+    // 'blockStart' isn't 'auto' so compute its value
+    offsets.BStart(aWM) = nsLayoutUtils::
+      ComputeBSizeDependentValue(aCBSize.BSize(aWM),
+                                 position->mOffset.Get(blockStart));
+
+    // Computed value for 'blockEnd' is minus the value of 'blockStart'
+    offsets.BEnd(aWM) = -offsets.BStart(aWM);
+  }
+
+  // Convert the offsets to physical coordinates and store them on the frame
+  aComputedOffsets = offsets.GetPhysicalMargin(aWM);
+  FrameProperties props = aFrame->Properties();
+  nsMargin* physicalOffsets = props.Get(nsIFrame::ComputedOffsetProperty());
+  if (physicalOffsets) {
+    *physicalOffsets = aComputedOffsets;
+  } else {
+    props.Set(nsIFrame::ComputedOffsetProperty(),
+              new nsMargin(aComputedOffsets));
+  }
+}
+
+/* static */ void
+ReflowInput::ApplyRelativePositioning(nsIFrame* aFrame,
+                                            const nsMargin& aComputedOffsets,
+                                            nsPoint* aPosition)
+{
+  if (!aFrame->IsRelativelyPositioned()) {
+    NS_ASSERTION(!aFrame->Properties().Get(nsIFrame::NormalPositionProperty()),
+                 "We assume that changing the 'position' property causes "
+                 "frame reconstruction.  If that ever changes, this code "
+                 "should call "
+                 "props.Delete(nsIFrame::NormalPositionProperty())");
+    return;
+  }
+
+  // Store the normal position
+  FrameProperties props = aFrame->Properties();
+  nsPoint* normalPosition = props.Get(nsIFrame::NormalPositionProperty());
+  if (normalPosition) {
+    *normalPosition = *aPosition;
+  } else {
+    props.Set(nsIFrame::NormalPositionProperty(), new nsPoint(*aPosition));
+  }
+
+  const nsStyleDisplay* display = aFrame->StyleDisplay();
+  if (NS_STYLE_POSITION_RELATIVE == display->mPosition) {
+    *aPosition += nsPoint(aComputedOffsets.left, aComputedOffsets.top);
+  } else if (NS_STYLE_POSITION_STICKY == display->mPosition &&
+             !aFrame->GetNextContinuation() &&
+             !aFrame->GetPrevContinuation() &&
+             !(aFrame->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT)) {
+    // Sticky positioning for elements with multiple frames needs to be
+    // computed all at once. We can't safely do that here because we might be
+    // partway through (re)positioning the frames, so leave it until the scroll
+    // container reflows and calls StickyScrollContainer::UpdatePositions.
+    // For single-frame sticky positioned elements, though, go ahead and apply
+    // it now to avoid unnecessary overflow updates later.
+    StickyScrollContainer* ssc =
+      StickyScrollContainer::GetStickyScrollContainerForFrame(aFrame);
+    if (ssc) {
+      *aPosition = ssc->ComputePosition(aFrame);
+    }
+  }
+}
+
+nsIFrame*
+ReflowInput::GetHypotheticalBoxContainer(nsIFrame*    aFrame,
+                                               nscoord&     aCBIStartEdge,
+                                               LogicalSize& aCBSize) const
+{
+  aFrame = aFrame->GetContainingBlock();
+  NS_ASSERTION(aFrame != mFrame, "How did that happen?");
+
+  /* Now aFrame is the containing block we want */
+
+  /* Check whether the containing block is currently being reflowed.
+     If so, use the info from the reflow state. */
+  const ReflowInput* state;
+  if (aFrame->GetStateBits() & NS_FRAME_IN_REFLOW) {
+    for (state = mParentReflowInput; state && state->mFrame != aFrame;
+         state = state->mParentReflowInput) {
+      /* do nothing */
+    }
+  } else {
+    state = nullptr;
+  }
+
+  if (state) {
+    WritingMode wm = state->GetWritingMode();
+    NS_ASSERTION(wm == aFrame->GetWritingMode(), "unexpected writing mode");
+    aCBIStartEdge = state->ComputedLogicalBorderPadding().IStart(wm);
+    aCBSize = state->ComputedSize(wm);
+  } else {
+    /* Didn't find a reflow state for aFrame.  Just compute the information we
+       want, on the assumption that aFrame already knows its size.  This really
+       ought to be true by now. */
+    NS_ASSERTION(!(aFrame->GetStateBits() & NS_FRAME_IN_REFLOW),
+                 "aFrame shouldn't be in reflow; we'll lie if it is");
+    WritingMode wm = aFrame->GetWritingMode();
+    LogicalMargin borderPadding = aFrame->GetLogicalUsedBorderAndPadding(wm);
+    aCBIStartEdge = borderPadding.IStart(wm);
+    aCBSize = aFrame->GetLogicalSize(wm) - borderPadding.Size(wm);
+  }
+
+  return aFrame;
+}
+
+struct nsHypotheticalPosition {
+  // offset from inline-start edge of containing block (which is a padding edge)
+  nscoord       mIStart;
+  // offset from block-start edge of containing block (which is a padding edge)
+  nscoord       mBStart;
+  WritingMode   mWritingMode;
+};
+
+static bool
+GetIntrinsicSizeFor(nsIFrame* aFrame, nsSize& aIntrinsicSize, nsIAtom* aFrameType)
+{
+  // See if it is an image frame
+  bool success = false;
+
+  // Currently the only type of replaced frame that we can get the intrinsic
+  // size for is an image frame
+  // XXX We should add back the GetReflowOutput() function and one of the
+  // things should be the intrinsic size...
+  if (aFrameType == nsGkAtoms::imageFrame) {
+    nsImageFrame* imageFrame = (nsImageFrame*)aFrame;
+
+    if (NS_SUCCEEDED(imageFrame->GetIntrinsicImageSize(aIntrinsicSize))) {
+      success = (aIntrinsicSize != nsSize(0, 0));
+    }
+  }
+  return success;
+}
+
+/**
+ * aInsideBoxSizing returns the part of the padding, border, and margin
+ * in the aAxis dimension that goes inside the edge given by box-sizing;
+ * aOutsideBoxSizing returns the rest.
+ */
+void
+ReflowInput::CalculateBorderPaddingMargin(
+                       LogicalAxis aAxis,
+                       nscoord aContainingBlockSize,
+                       nscoord* aInsideBoxSizing,
+                       nscoord* aOutsideBoxSizing) const
+{
+  WritingMode wm = GetWritingMode();
+  mozilla::css::Side startSide =
+    wm.PhysicalSide(MakeLogicalSide(aAxis, eLogicalEdgeStart));
+  mozilla::css::Side endSide =
+    wm.PhysicalSide(MakeLogicalSide(aAxis, eLogicalEdgeEnd));
+
+  nsMargin styleBorder = mStyleBorder->GetComputedBorder();
+  nscoord borderStartEnd =
+    styleBorder.Side(startSide) + styleBorder.Side(endSide);
+
+  nscoord paddingStartEnd, marginStartEnd;
+
+  // See if the style system can provide us the padding directly
+  nsMargin stylePadding;
+  if (mStylePadding->GetPadding(stylePadding)) {
+    paddingStartEnd =
+      stylePadding.Side(startSide) + stylePadding.Side(endSide);
+  } else {
+    // We have to compute the start and end values
+    nscoord start, end;
+    start = nsLayoutUtils::
+      ComputeCBDependentValue(aContainingBlockSize,
+                              mStylePadding->mPadding.Get(startSide));
+    end = nsLayoutUtils::
+      ComputeCBDependentValue(aContainingBlockSize,
+                              mStylePadding->mPadding.Get(endSide));
+    paddingStartEnd = start + end;
+  }
+
+  // See if the style system can provide us the margin directly
+  nsMargin styleMargin;
+  if (mStyleMargin->GetMargin(styleMargin)) {
+    marginStartEnd =
+      styleMargin.Side(startSide) + styleMargin.Side(endSide);
+  } else {
+    nscoord start, end;
+    // We have to compute the start and end values
+    if (eStyleUnit_Auto == mStyleMargin->mMargin.GetUnit(startSide)) {
+      // XXX FIXME (or does CalculateBlockSideMargins do this?)
+      start = 0;  // just ignore
+    } else {
+      start = nsLayoutUtils::
+        ComputeCBDependentValue(aContainingBlockSize,
+                                mStyleMargin->mMargin.Get(startSide));
+    }
+    if (eStyleUnit_Auto == mStyleMargin->mMargin.GetUnit(endSide)) {
+      // XXX FIXME (or does CalculateBlockSideMargins do this?)
+      end = 0;  // just ignore
+    } else {
+      end = nsLayoutUtils::
+        ComputeCBDependentValue(aContainingBlockSize,
+                                mStyleMargin->mMargin.Get(endSide));
+    }
+    marginStartEnd = start + end;
+  }
+
+  nscoord outside = paddingStartEnd + borderStartEnd + marginStartEnd;
+  nscoord inside = 0;
+  if (mStylePosition->mBoxSizing == StyleBoxSizing::Border) {
+    inside = borderStartEnd + paddingStartEnd;
+  }
+  outside -= inside;
+  *aInsideBoxSizing = inside;
+  *aOutsideBoxSizing = outside;
+  return;
+}
+
+/**
+ * Returns true iff a pre-order traversal of the normal child
+ * frames rooted at aFrame finds no non-empty frame before aDescendant.
+ */
+static bool AreAllEarlierInFlowFramesEmpty(nsIFrame* aFrame,
+  nsIFrame* aDescendant, bool* aFound) {
+  if (aFrame == aDescendant) {
+    *aFound = true;
+    return true;
+  }
+  if (!aFrame->IsSelfEmpty()) {
+    *aFound = false;
+    return false;
+  }
+  for (nsIFrame* f : aFrame->PrincipalChildList()) {
+    bool allEmpty = AreAllEarlierInFlowFramesEmpty(f, aDescendant, aFound);
+    if (*aFound || !allEmpty) {
+      return allEmpty;
+    }
+  }
+  *aFound = false;
+  return true;
+}
+
+// Calculate the position of the hypothetical box that the element would have
+// if it were in the flow.
+// The values returned are relative to the padding edge of the absolute
+// containing block. The writing-mode of the hypothetical box position will
+// have the same block direction as the absolute containing block, but may
+// differ in inline-bidi direction.
+// In the code below, |cbrs->frame| is the absolute containing block, while
+// |containingBlock| is the nearest block container of the placeholder frame,
+// which may be different from the absolute containing block.
+void
+ReflowInput::CalculateHypotheticalPosition
+                     (nsPresContext*           aPresContext,
+                      nsIFrame*                aPlaceholderFrame,
+                      const ReflowInput* cbrs,
+                      nsHypotheticalPosition&  aHypotheticalPos,
+                      nsIAtom*                 aFrameType) const
+{
+  NS_ASSERTION(mStyleDisplay->mOriginalDisplay != StyleDisplay::None,
+               "mOriginalDisplay has not been properly initialized");
+
+  // Find the nearest containing block frame to the placeholder frame,
+  // and its inline-start edge and width.
+  nscoord blockIStartContentEdge;
+  // Dummy writing mode for blockContentSize, will be changed as needed by
+  // GetHypotheticalBoxContainer.
+  WritingMode cbwm = cbrs->GetWritingMode();
+  LogicalSize blockContentSize(cbwm);
+  nsIFrame* containingBlock =
+    GetHypotheticalBoxContainer(aPlaceholderFrame, blockIStartContentEdge,
+                                blockContentSize);
+  // Now blockContentSize is in containingBlock's writing mode.
+
+  // If it's a replaced element and it has a 'auto' value for
+  //'inline size', see if we can get the intrinsic size. This will allow
+  // us to exactly determine both the inline edges
+  WritingMode wm = containingBlock->GetWritingMode();
+
+  nsStyleCoord styleISize = mStylePosition->ISize(wm);
+  bool isAutoISize = styleISize.GetUnit() == eStyleUnit_Auto;
+  nsSize      intrinsicSize;
+  bool        knowIntrinsicSize = false;
+  if (NS_FRAME_IS_REPLACED(mFrameType) && isAutoISize) {
+    // See if we can get the intrinsic size of the element
+    knowIntrinsicSize = GetIntrinsicSizeFor(mFrame, intrinsicSize, aFrameType);
+  }
+
+  // See if we can calculate what the box inline size would have been if
+  // the element had been in the flow
+  nscoord boxISize;
+  bool    knowBoxISize = false;
+  if ((StyleDisplay::Inline == mStyleDisplay->mOriginalDisplay) &&
+      !NS_FRAME_IS_REPLACED(mFrameType)) {
+    // For non-replaced inline-level elements the 'inline size' property
+    // doesn't apply, so we don't know what the inline size would have
+    // been without reflowing it
+
+  } else {
+    // It's either a replaced inline-level element or a block-level element
+
+    // Determine the total amount of inline direction
+    // border/padding/margin that the element would have had if it had
+    // been in the flow. Note that we ignore any 'auto' and 'inherit'
+    // values
+    nscoord insideBoxSizing, outsideBoxSizing;
+    CalculateBorderPaddingMargin(eLogicalAxisInline,
+                                 blockContentSize.ISize(wm),
+                                 &insideBoxSizing, &outsideBoxSizing);
+
+    if (NS_FRAME_IS_REPLACED(mFrameType) && isAutoISize) {
+      // It's a replaced element with an 'auto' inline size so the box
+      // inline size is its intrinsic size plus any border/padding/margin
+      if (knowIntrinsicSize) {
+        boxISize = LogicalSize(wm, intrinsicSize).ISize(wm) +
+                   outsideBoxSizing + insideBoxSizing;
+        knowBoxISize = true;
+      }
+
+    } else if (isAutoISize) {
+      // The box inline size is the containing block inline size
+      boxISize = blockContentSize.ISize(wm);
+      knowBoxISize = true;
+
+    } else {
+      // We need to compute it. It's important we do this, because if it's
+      // percentage based this computed value may be different from the computed
+      // value calculated using the absolute containing block width
+      boxISize = ComputeISizeValue(blockContentSize.ISize(wm),
+                                   insideBoxSizing, outsideBoxSizing,
+                                   styleISize) +
+                 insideBoxSizing + outsideBoxSizing;
+      knowBoxISize = true;
+    }
+  }
+
+  // Get the placeholder x-offset and y-offset in the coordinate
+  // space of its containing block
+  // XXXbz the placeholder is not fully reflowed yet if our containing block is
+  // relatively positioned...
+  nsSize containerSize = containingBlock->GetStateBits() & NS_FRAME_IN_REFLOW
+    ? cbrs->ComputedSizeAsContainerIfConstrained()
+    : containingBlock->GetSize();
+  LogicalPoint
+    placeholderOffset(wm, aPlaceholderFrame->GetOffsetTo(containingBlock),
+                      containerSize);
+
+  // First, determine the hypothetical box's mBStart.  We want to check the
+  // content insertion frame of containingBlock for block-ness, but make
+  // sure to compute all coordinates in the coordinate system of
+  // containingBlock.
+  nsBlockFrame* blockFrame =
+    nsLayoutUtils::GetAsBlock(containingBlock->GetContentInsertionFrame());
+  if (blockFrame) {
+    // Use a null containerSize to convert a LogicalPoint functioning as a
+    // vector into a physical nsPoint vector.
+    const nsSize nullContainerSize;
+    LogicalPoint blockOffset(wm, blockFrame->GetOffsetTo(containingBlock),
+                             nullContainerSize);
+    bool isValid;
+    nsBlockInFlowLineIterator iter(blockFrame, aPlaceholderFrame, &isValid);
+    if (!isValid) {
+      // Give up.  We're probably dealing with somebody using
+      // position:absolute inside native-anonymous content anyway.
+      aHypotheticalPos.mBStart = placeholderOffset.B(wm);
+    } else {
+      NS_ASSERTION(iter.GetContainer() == blockFrame,
+                   "Found placeholder in wrong block!");
+      nsBlockFrame::LineIterator lineBox = iter.GetLine();
+
+      // How we determine the hypothetical box depends on whether the element
+      // would have been inline-level or block-level
+      LogicalRect lineBounds =
+        lineBox->GetBounds().ConvertTo(wm, lineBox->mWritingMode,
+                                       lineBox->mContainerSize);
+      if (mStyleDisplay->IsOriginalDisplayInlineOutsideStyle()) {
+        // Use the block-start of the inline box which the placeholder lives in
+        // as the hypothetical box's block-start.
+        aHypotheticalPos.mBStart = lineBounds.BStart(wm) + blockOffset.B(wm);
+      } else {
+        // The element would have been block-level which means it would
+        // be below the line containing the placeholder frame, unless
+        // all the frames before it are empty.  In that case, it would
+        // have been just before this line.
+        // XXXbz the line box is not fully reflowed yet if our
+        // containing block is relatively positioned...
+        if (lineBox != iter.End()) {
+          nsIFrame * firstFrame = lineBox->mFirstChild;
+          bool found = false;
+          bool allEmpty = true;
+          while (firstFrame) { // See bug 223064
+            allEmpty = AreAllEarlierInFlowFramesEmpty(firstFrame,
+              aPlaceholderFrame, &found);
+            if (found || !allEmpty)
+              break;
+            firstFrame = firstFrame->GetNextSibling();
+          }
+          NS_ASSERTION(firstFrame, "Couldn't find placeholder!");
+
+          if (allEmpty) {
+            // The top of the hypothetical box is the top of the line
+            // containing the placeholder, since there is nothing in the
+            // line before our placeholder except empty frames.
+            aHypotheticalPos.mBStart =
+              lineBounds.BStart(wm) + blockOffset.B(wm);
+          } else {
+            // The top of the hypothetical box is just below the line
+            // containing the placeholder.
+            aHypotheticalPos.mBStart =
+              lineBounds.BEnd(wm) + blockOffset.B(wm);
+          }
+        } else {
+          // Just use the placeholder's block-offset wrt the containing block
+          aHypotheticalPos.mBStart = placeholderOffset.B(wm);
+        }
+      }
+    }
+  } else {
+    // The containing block is not a block, so it's probably something
+    // like a XUL box, etc.
+    // Just use the placeholder's block-offset
+    aHypotheticalPos.mBStart = placeholderOffset.B(wm);
+  }
+
+  // Second, determine the hypothetical box's mIStart.
+  // How we determine the hypothetical box depends on whether the element
+  // would have been inline-level or block-level
+  if (mStyleDisplay->IsOriginalDisplayInlineOutsideStyle() ||
+      mFlags.mIOffsetsNeedCSSAlign) {
+    // The placeholder represents the IStart edge of the hypothetical box.
+    // (Or if mFlags.mIOffsetsNeedCSSAlign is set, it represents the IStart
+    // edge of the Alignment Container.)
+    aHypotheticalPos.mIStart = placeholderOffset.I(wm);
+  } else {
+    aHypotheticalPos.mIStart = blockIStartContentEdge;
+  }
+
+  // The current coordinate space is that of the nearest block to the placeholder.
+  // Convert to the coordinate space of the absolute containing block
+  // One weird thing here is that for fixed-positioned elements we want to do
+  // the conversion incorrectly; specifically we want to ignore any scrolling
+  // that may have happened;
+  nsPoint cbOffset;
+  if (mStyleDisplay->mPosition == NS_STYLE_POSITION_FIXED &&
+      // Exclude cases inside -moz-transform where fixed is like absolute.
+      nsLayoutUtils::IsReallyFixedPos(mFrame)) {
+    // In this case, cbrs->frame will likely be an ancestor of
+    // containingBlock, so can just walk our way up the frame tree.
+    // Make sure to not add positions of frames whose parent is a
+    // scrollFrame, since we're doing fixed positioning, which assumes
+    // everything is scrolled to (0,0).
+    cbOffset.MoveTo(0, 0);
+    do {
+      cbOffset += containingBlock->GetPositionIgnoringScrolling();
+      nsContainerFrame* parent = containingBlock->GetParent();
+      if (!parent) {
+        // Oops, our absolute containing block isn't an ancestor of the
+        // placeholder's containing block. This can happen if the placeholder
+        // is pushed to a different page in a printing context.  'cbOffset' is
+        // currently relative to the root frame (containingBlock) - so just
+        // subtract the offset to the absolute containing block to make it
+        // relative to that.
+        cbOffset -= containingBlock->GetOffsetTo(cbrs->mFrame);
+        break;
+      }
+      containingBlock = parent;
+    } while (containingBlock != cbrs->mFrame);
+  } else {
+    // XXXldb We need to either ignore scrolling for the absolute
+    // positioning case too (and take the incompatibility) or figure out
+    // how to make these positioned elements actually *move* when we
+    // scroll, and thus avoid the resulting incremental reflow bugs.
+    cbOffset = containingBlock->GetOffsetTo(cbrs->mFrame);
+  }
+  nsSize cbrsSize = cbrs->ComputedSizeAsContainerIfConstrained();
+  LogicalPoint logCBOffs(wm, cbOffset, cbrsSize - containerSize);
+  aHypotheticalPos.mIStart += logCBOffs.I(wm);
+  aHypotheticalPos.mBStart += logCBOffs.B(wm);
+
+  // The specified offsets are relative to the absolute containing block's
+  // padding edge and our current values are relative to the border edge, so
+  // translate.
+  LogicalMargin border =
+    cbrs->ComputedLogicalBorderPadding() - cbrs->ComputedLogicalPadding();
+  border = border.ConvertTo(wm, cbrs->GetWritingMode());
+  aHypotheticalPos.mIStart -= border.IStart(wm);
+  aHypotheticalPos.mBStart -= border.BStart(wm);
+
+  // At this point, we have computed aHypotheticalPos using the writing mode
+  // of the placeholder's containing block.
+
+  if (cbwm.GetBlockDir() != wm.GetBlockDir()) {
+    // If the block direction we used in calculating aHypotheticalPos does not
+    // match the absolute containing block's, we need to convert here so that
+    // aHypotheticalPos is usable in relation to the absolute containing block.
+    // This requires computing or measuring the abspos frame's block-size,
+    // which is not otherwise required/used here (as aHypotheticalPos
+    // records only the block-start coordinate).
+
+    // This is similar to the inline-size calculation for a replaced
+    // inline-level element or a block-level element (above), except that
+    // 'auto' sizing is handled differently in the block direction for non-
+    // replaced elements and replaced elements lacking an intrinsic size.
+
+    // Determine the total amount of block direction
+    // border/padding/margin that the element would have had if it had
+    // been in the flow. Note that we ignore any 'auto' and 'inherit'
+    // values.
+    nscoord insideBoxSizing, outsideBoxSizing;
+    CalculateBorderPaddingMargin(eLogicalAxisBlock,
+                                 blockContentSize.BSize(wm),
+                                 &insideBoxSizing, &outsideBoxSizing);
+
+    nscoord boxBSize;
+    nsStyleCoord styleBSize = mStylePosition->BSize(wm);
+    bool isAutoBSize = styleBSize.GetUnit() == eStyleUnit_Auto;
+    if (isAutoBSize) {
+      if (NS_FRAME_IS_REPLACED(mFrameType) && knowIntrinsicSize) {
+        // It's a replaced element with an 'auto' block size so the box
+        // block size is its intrinsic size plus any border/padding/margin
+        boxBSize = LogicalSize(wm, intrinsicSize).BSize(wm) +
+                   outsideBoxSizing + insideBoxSizing;
+      } else {
+        // XXX Bug 1191801
+        // Figure out how to get the correct boxBSize here (need to reflow the
+        // positioned frame?)
+        boxBSize = 0;
+      }
+    } else {
+      // We need to compute it. It's important we do this, because if it's
+      // percentage-based this computed value may be different from the
+      // computed value calculated using the absolute containing block height.
+      boxBSize = nsLayoutUtils::ComputeBSizeValue(blockContentSize.BSize(wm),
+                                                  insideBoxSizing, styleBSize) +
+                 insideBoxSizing + outsideBoxSizing;
+    }
+
+    LogicalSize boxSize(wm, knowBoxISize ? boxISize : 0, boxBSize);
+
+    LogicalPoint origin(wm, aHypotheticalPos.mIStart,
+                        aHypotheticalPos.mBStart);
+    origin = origin.ConvertTo(cbwm, wm, cbrsSize -
+                              boxSize.GetPhysicalSize(wm));
+
+    aHypotheticalPos.mIStart = origin.I(cbwm);
+    aHypotheticalPos.mBStart = origin.B(cbwm);
+    aHypotheticalPos.mWritingMode = cbwm;
+  } else {
+    aHypotheticalPos.mWritingMode = wm;
+  }
+}
+
+void
+ReflowInput::InitAbsoluteConstraints(nsPresContext* aPresContext,
+                                           const ReflowInput* cbrs,
+                                           const LogicalSize& aCBSize,
+                                           nsIAtom* aFrameType)
+{
+  WritingMode wm = GetWritingMode();
+  WritingMode cbwm = cbrs->GetWritingMode();
+  NS_PRECONDITION(aCBSize.BSize(cbwm) != NS_AUTOHEIGHT,
+                  "containing block bsize must be constrained");
+
+  NS_ASSERTION(aFrameType != nsGkAtoms::tableFrame,
+               "InitAbsoluteConstraints should not be called on table frames");
+  NS_ASSERTION(mFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW,
+               "Why are we here?");
+
+  const auto& styleOffset = mStylePosition->mOffset;
+  bool iStartIsAuto = styleOffset.GetIStartUnit(cbwm) == eStyleUnit_Auto;
+  bool iEndIsAuto   = styleOffset.GetIEndUnit(cbwm) == eStyleUnit_Auto;
+  bool bStartIsAuto = styleOffset.GetBStartUnit(cbwm) == eStyleUnit_Auto;
+  bool bEndIsAuto   = styleOffset.GetBEndUnit(cbwm) == eStyleUnit_Auto;
+
+  // If both 'left' and 'right' are 'auto' or both 'top' and 'bottom' are
+  // 'auto', then compute the hypothetical box position where the element would
+  // have been if it had been in the flow
+  nsHypotheticalPosition hypotheticalPos;
+  if ((iStartIsAuto && iEndIsAuto) || (bStartIsAuto && bEndIsAuto)) {
+    nsIFrame* placeholderFrame =
+      aPresContext->PresShell()->GetPlaceholderFrameFor(mFrame);
+    NS_ASSERTION(placeholderFrame, "no placeholder frame");
+
+    if (placeholderFrame->HasAnyStateBits(
+          PLACEHOLDER_STATICPOS_NEEDS_CSSALIGN)) {
+      DebugOnly<nsIFrame*> placeholderParent = placeholderFrame->GetParent();
+      MOZ_ASSERT(placeholderParent, "shouldn't have unparented placeholders");
+      MOZ_ASSERT(placeholderParent->IsFlexOrGridContainer(),
+                 "This flag should only be set on grid/flex children");
+
+      // If the (as-yet unknown) static position will determine the inline
+      // and/or block offsets, set flags to note those offsets aren't valid
+      // until we can do CSS Box Alignment on the OOF frame.
+      mFlags.mIOffsetsNeedCSSAlign = (iStartIsAuto && iEndIsAuto);
+      mFlags.mBOffsetsNeedCSSAlign = (bStartIsAuto && bEndIsAuto);
+    }
+
+    if (mFlags.mStaticPosIsCBOrigin) {
+      hypotheticalPos.mWritingMode = cbwm;
+      hypotheticalPos.mIStart = nscoord(0);
+      hypotheticalPos.mBStart = nscoord(0);
+    } else {
+      CalculateHypotheticalPosition(aPresContext, placeholderFrame, cbrs,
+                                    hypotheticalPos, aFrameType);
+    }
+  }
+
+  // Initialize the 'left' and 'right' computed offsets
+  // XXX Handle new 'static-position' value...
+
+  // Size of the containing block in its writing mode
+  LogicalSize cbSize = aCBSize;
+  LogicalMargin offsets = ComputedLogicalOffsets().ConvertTo(cbwm, wm);
+
+  if (iStartIsAuto) {
+    offsets.IStart(cbwm) = 0;
+  } else {
+    offsets.IStart(cbwm) = nsLayoutUtils::
+      ComputeCBDependentValue(cbSize.ISize(cbwm), styleOffset.GetIStart(cbwm));
+  }
+  if (iEndIsAuto) {
+    offsets.IEnd(cbwm) = 0;
+  } else {
+    offsets.IEnd(cbwm) = nsLayoutUtils::
+      ComputeCBDependentValue(cbSize.ISize(cbwm), styleOffset.GetIEnd(cbwm));
+  }
+
+  if (iStartIsAuto && iEndIsAuto) {
+    if (cbwm.IsBidiLTR() != hypotheticalPos.mWritingMode.IsBidiLTR()) {
+      offsets.IEnd(cbwm) = hypotheticalPos.mIStart;
+      iEndIsAuto = false;
+    } else {
+      offsets.IStart(cbwm) = hypotheticalPos.mIStart;
+      iStartIsAuto = false;
+    }
+  }
+
+  if (bStartIsAuto) {
+    offsets.BStart(cbwm) = 0;
+  } else {
+    offsets.BStart(cbwm) = nsLayoutUtils::
+      ComputeBSizeDependentValue(cbSize.BSize(cbwm),
+                                 styleOffset.GetBStart(cbwm));
+  }
+  if (bEndIsAuto) {
+    offsets.BEnd(cbwm) = 0;
+  } else {
+    offsets.BEnd(cbwm) = nsLayoutUtils::
+      ComputeBSizeDependentValue(cbSize.BSize(cbwm),
+                                 styleOffset.GetBEnd(cbwm));
+  }
+
+  if (bStartIsAuto && bEndIsAuto) {
+    // Treat 'top' like 'static-position'
+    offsets.BStart(cbwm) = hypotheticalPos.mBStart;
+    bStartIsAuto = false;
+  }
+
+  SetComputedLogicalOffsets(offsets.ConvertTo(wm, cbwm));
+
+  typedef nsIFrame::ComputeSizeFlags ComputeSizeFlags;
+  ComputeSizeFlags computeSizeFlags = ComputeSizeFlags::eDefault;
+  if (mFlags.mIClampMarginBoxMinSize) {
+    computeSizeFlags = ComputeSizeFlags(computeSizeFlags |
+                         ComputeSizeFlags::eIClampMarginBoxMinSize);
+  }
+  if (mFlags.mBClampMarginBoxMinSize) {
+    computeSizeFlags = ComputeSizeFlags(computeSizeFlags |
+                         ComputeSizeFlags::eBClampMarginBoxMinSize);
+  }
+  if (mFlags.mShrinkWrap) {
+    computeSizeFlags =
+      ComputeSizeFlags(computeSizeFlags | ComputeSizeFlags::eShrinkWrap);
+  }
+  if (mFlags.mUseAutoBSize) {
+    computeSizeFlags =
+      ComputeSizeFlags(computeSizeFlags | ComputeSizeFlags::eUseAutoBSize);
+  }
+  if (wm.IsOrthogonalTo(cbwm)) {
+    if (bStartIsAuto || bEndIsAuto) {
+      computeSizeFlags =
+        ComputeSizeFlags(computeSizeFlags | ComputeSizeFlags::eShrinkWrap);
+    }
+  } else {
+    if (iStartIsAuto || iEndIsAuto) {
+      computeSizeFlags =
+        ComputeSizeFlags(computeSizeFlags | ComputeSizeFlags::eShrinkWrap);
+    }
+  }
+
+  LogicalSize computedSize(wm);
+  {
+    AutoMaybeDisableFontInflation an(mFrame);
+
+    computedSize =
+      mFrame->ComputeSize(mRenderingContext, wm, cbSize.ConvertTo(wm, cbwm),
+                         cbSize.ConvertTo(wm, cbwm).ISize(wm), // XXX or AvailableISize()?
+                         ComputedLogicalMargin().Size(wm) +
+                           ComputedLogicalOffsets().Size(wm),
+                         ComputedLogicalBorderPadding().Size(wm) -
+                           ComputedLogicalPadding().Size(wm),
+                         ComputedLogicalPadding().Size(wm),
+                         computeSizeFlags);
+    ComputedISize() = computedSize.ISize(wm);
+    ComputedBSize() = computedSize.BSize(wm);
+    NS_ASSERTION(ComputedISize() >= 0, "Bogus inline-size");
+    NS_ASSERTION(ComputedBSize() == NS_UNCONSTRAINEDSIZE ||
+                 ComputedBSize() >= 0, "Bogus block-size");
+  }
+  computedSize = computedSize.ConvertTo(cbwm, wm);
+
+  // XXX Now that we have ComputeSize, can we condense many of the
+  // branches off of widthIsAuto?
+
+  LogicalMargin margin = ComputedLogicalMargin().ConvertTo(cbwm, wm);
+  const LogicalMargin borderPadding =
+    ComputedLogicalBorderPadding().ConvertTo(cbwm, wm);
+
+  bool iSizeIsAuto = eStyleUnit_Auto == mStylePosition->ISize(cbwm).GetUnit();
+  if (iStartIsAuto) {
+    // We know 'right' is not 'auto' anymore thanks to the hypothetical
+    // box code above.
+    // Solve for 'left'.
+    if (iSizeIsAuto) {
+      // XXXldb This, and the corresponding code in
+      // nsAbsoluteContainingBlock.cpp, could probably go away now that
+      // we always compute widths.
+      offsets.IStart(cbwm) = NS_AUTOOFFSET;
+    } else {
+      offsets.IStart(cbwm) =
+        cbSize.ISize(cbwm) - offsets.IEnd(cbwm) -
+        computedSize.ISize(cbwm) - margin.IStartEnd(cbwm) -
+        borderPadding.IStartEnd(cbwm);
+    }
+  } else if (iEndIsAuto) {
+    // We know 'left' is not 'auto' anymore thanks to the hypothetical
+    // box code above.
+    // Solve for 'right'.
+    if (iSizeIsAuto) {
+      // XXXldb This, and the corresponding code in
+      // nsAbsoluteContainingBlock.cpp, could probably go away now that
+      // we always compute widths.
+      offsets.IEnd(cbwm) = NS_AUTOOFFSET;
+    } else {
+      offsets.IEnd(cbwm) =
+        cbSize.ISize(cbwm) - offsets.IStart(cbwm) -
+        computedSize.ISize(cbwm) - margin.IStartEnd(cbwm) -
+        borderPadding.IStartEnd(cbwm);
+    }
+  } else {
+    // Neither 'inline-start' nor 'inline-end' is 'auto'.
+
+    if (wm.IsOrthogonalTo(cbwm)) {
+      // For orthogonal blocks, we need to handle the case where the block had
+      // unconstrained block-size, which mapped to unconstrained inline-size
+      // in the containing block's writing mode.
+      nscoord autoISize = cbSize.ISize(cbwm) - margin.IStartEnd(cbwm) -
+        borderPadding.IStartEnd(cbwm) - offsets.IStartEnd(cbwm);
+      if (autoISize < 0) {
+        autoISize = 0;
+      }
+
+      if (computedSize.ISize(cbwm) == NS_UNCONSTRAINEDSIZE) {
+        // For non-replaced elements with block-size auto, the block-size
+        // fills the remaining space.
+        computedSize.ISize(cbwm) = autoISize;
+
+        // XXX Do these need box-sizing adjustments?
+        LogicalSize maxSize = ComputedMaxSize(cbwm);
+        LogicalSize minSize = ComputedMinSize(cbwm);
+        if (computedSize.ISize(cbwm) > maxSize.ISize(cbwm)) {
+          computedSize.ISize(cbwm) = maxSize.ISize(cbwm);
+        }
+        if (computedSize.ISize(cbwm) < minSize.ISize(cbwm)) {
+          computedSize.ISize(cbwm) = minSize.ISize(cbwm);
+        }
+      }
+    }
+
+    // However, the inline-size might
+    // still not fill all the available space (even though we didn't
+    // shrink-wrap) in case:
+    //  * inline-size was specified
+    //  * we're dealing with a replaced element
+    //  * width was constrained by min- or max-inline-size.
+
+    nscoord availMarginSpace =
+      aCBSize.ISize(cbwm) - offsets.IStartEnd(cbwm) - margin.IStartEnd(cbwm) -
+      borderPadding.IStartEnd(cbwm) - computedSize.ISize(cbwm);
+    bool marginIStartIsAuto =
+      eStyleUnit_Auto == mStyleMargin->mMargin.GetIStartUnit(cbwm);
+    bool marginIEndIsAuto =
+      eStyleUnit_Auto == mStyleMargin->mMargin.GetIEndUnit(cbwm);
+
+    if (marginIStartIsAuto) {
+      if (marginIEndIsAuto) {
+        if (availMarginSpace < 0) {
+          // Note that this case is different from the neither-'auto'
+          // case below, where the spec says to ignore 'left'/'right'.
+          // Ignore the specified value for 'margin-right'.
+          margin.IEnd(cbwm) = availMarginSpace;
+        } else {
+          // Both 'margin-left' and 'margin-right' are 'auto', so they get
+          // equal values
+          margin.IStart(cbwm) = availMarginSpace / 2;
+          margin.IEnd(cbwm) = availMarginSpace - margin.IStart(cbwm);
+        }
+      } else {
+        // Just 'margin-left' is 'auto'
+        margin.IStart(cbwm) = availMarginSpace;
+      }
+    } else {
+      if (marginIEndIsAuto) {
+        // Just 'margin-right' is 'auto'
+        margin.IEnd(cbwm) = availMarginSpace;
+      } else {
+        // We're over-constrained so use the direction of the containing
+        // block to dictate which value to ignore.  (And note that the
+        // spec says to ignore 'left' or 'right' rather than
+        // 'margin-left' or 'margin-right'.)
+        // Note that this case is different from the both-'auto' case
+        // above, where the spec says to ignore
+        // 'margin-left'/'margin-right'.
+        // Ignore the specified value for 'right'.
+        offsets.IEnd(cbwm) += availMarginSpace;
+      }
+    }
+  }
+
+  bool bSizeIsAuto = eStyleUnit_Auto == mStylePosition->BSize(cbwm).GetUnit();
+  if (bStartIsAuto) {
+    // solve for block-start
+    if (bSizeIsAuto) {
+      offsets.BStart(cbwm) = NS_AUTOOFFSET;
+    } else {
+      offsets.BStart(cbwm) = cbSize.BSize(cbwm) - margin.BStartEnd(cbwm) -
+        borderPadding.BStartEnd(cbwm) - computedSize.BSize(cbwm) -
+        offsets.BEnd(cbwm);
+    }
+  } else if (bEndIsAuto) {
+    // solve for block-end
+    if (bSizeIsAuto) {
+      offsets.BEnd(cbwm) = NS_AUTOOFFSET;
+    } else {
+      offsets.BEnd(cbwm) = cbSize.BSize(cbwm) - margin.BStartEnd(cbwm) -
+        borderPadding.BStartEnd(cbwm) - computedSize.BSize(cbwm) -
+        offsets.BStart(cbwm);
+    }
+  } else {
+    // Neither block-start nor -end is 'auto'.
+    nscoord autoBSize = cbSize.BSize(cbwm) - margin.BStartEnd(cbwm) -
+      borderPadding.BStartEnd(cbwm) - offsets.BStartEnd(cbwm);
+    if (autoBSize < 0) {
+      autoBSize = 0;
+    }
+
+    if (computedSize.BSize(cbwm) == NS_UNCONSTRAINEDSIZE) {
+      // For non-replaced elements with block-size auto, the block-size
+      // fills the remaining space.
+      computedSize.BSize(cbwm) = autoBSize;
+
+      // XXX Do these need box-sizing adjustments?
+      LogicalSize maxSize = ComputedMaxSize(cbwm);
+      LogicalSize minSize = ComputedMinSize(cbwm);
+      if (computedSize.BSize(cbwm) > maxSize.BSize(cbwm)) {
+        computedSize.BSize(cbwm) = maxSize.BSize(cbwm);
+      }
+      if (computedSize.BSize(cbwm) < minSize.BSize(cbwm)) {
+        computedSize.BSize(cbwm) = minSize.BSize(cbwm);
+      }
+    }
+
+    // The block-size might still not fill all the available space in case:
+    //  * bsize was specified
+    //  * we're dealing with a replaced element
+    //  * bsize was constrained by min- or max-bsize.
+    nscoord availMarginSpace = autoBSize - computedSize.BSize(cbwm);
+    bool marginBStartIsAuto =
+      eStyleUnit_Auto == mStyleMargin->mMargin.GetBStartUnit(cbwm);
+    bool marginBEndIsAuto =
+      eStyleUnit_Auto == mStyleMargin->mMargin.GetBEndUnit(cbwm);
+
+    if (marginBStartIsAuto) {
+      if (marginBEndIsAuto) {
+        // Both 'margin-top' and 'margin-bottom' are 'auto', so they get
+        // equal values
+        margin.BStart(cbwm) = availMarginSpace / 2;
+        margin.BEnd(cbwm) = availMarginSpace - margin.BStart(cbwm);
+      } else {
+        // Just margin-block-start is 'auto'
+        margin.BStart(cbwm) = availMarginSpace;
+      }
+    } else {
+      if (marginBEndIsAuto) {
+        // Just margin-block-end is 'auto'
+        margin.BEnd(cbwm) = availMarginSpace;
+      } else {
+        // We're over-constrained so ignore the specified value for
+        // block-end.  (And note that the spec says to ignore 'bottom'
+        // rather than 'margin-bottom'.)
+        offsets.BEnd(cbwm) += availMarginSpace;
+      }
+    }
+  }
+  ComputedBSize() = computedSize.ConvertTo(wm, cbwm).BSize(wm);
+  ComputedISize() = computedSize.ConvertTo(wm, cbwm).ISize(wm);
+
+  SetComputedLogicalOffsets(offsets.ConvertTo(wm, cbwm));
+  SetComputedLogicalMargin(margin.ConvertTo(wm, cbwm));
+}
+
+// This will not be converted to abstract coordinates because it's only
+// used in CalcQuirkContainingBlockHeight
+nscoord
+GetBlockMarginBorderPadding(const ReflowInput* aReflowInput)
+{
+  nscoord result = 0;
+  if (!aReflowInput) return result;
+
+  // zero auto margins
+  nsMargin margin = aReflowInput->ComputedPhysicalMargin();
+  if (NS_AUTOMARGIN == margin.top) 
+    margin.top = 0;
+  if (NS_AUTOMARGIN == margin.bottom) 
+    margin.bottom = 0;
+
+  result += margin.top + margin.bottom;
+  result += aReflowInput->ComputedPhysicalBorderPadding().top + 
+            aReflowInput->ComputedPhysicalBorderPadding().bottom;
+
+  return result;
+}
+
+/* Get the height based on the viewport of the containing block specified 
+ * in aReflowInput when the containing block has mComputedHeight == NS_AUTOHEIGHT
+ * This will walk up the chain of containing blocks looking for a computed height
+ * until it finds the canvas frame, or it encounters a frame that is not a block,
+ * area, or scroll frame. This handles compatibility with IE (see bug 85016 and bug 219693)
+ *
+ * When we encounter scrolledContent block frames, we skip over them,
+ * since they are guaranteed to not be useful for computing the containing block.
+ *
+ * See also IsQuirkContainingBlockHeight.
+ */
+static nscoord
+CalcQuirkContainingBlockHeight(const ReflowInput* aCBReflowInput)
+{
+  const ReflowInput* firstAncestorRI = nullptr; // a candidate for html frame
+  const ReflowInput* secondAncestorRI = nullptr; // a candidate for body frame
+  
+  // initialize the default to NS_AUTOHEIGHT as this is the containings block
+  // computed height when this function is called. It is possible that we 
+  // don't alter this height especially if we are restricted to one level
+  nscoord result = NS_AUTOHEIGHT; 
+                             
+  const ReflowInput* rs = aCBReflowInput;
+  for (; rs; rs = rs->mParentReflowInput) {
+    nsIAtom* frameType = rs->mFrame->GetType();
+    // if the ancestor is auto height then skip it and continue up if it 
+    // is the first block frame and possibly the body/html
+    if (nsGkAtoms::blockFrame == frameType ||
+#ifdef MOZ_XUL
+        nsGkAtoms::XULLabelFrame == frameType ||
+#endif
+        nsGkAtoms::scrollFrame == frameType) {
+
+      secondAncestorRI = firstAncestorRI;
+      firstAncestorRI = rs;
+
+      // If the current frame we're looking at is positioned, we don't want to
+      // go any further (see bug 221784).  The behavior we want here is: 1) If
+      // not auto-height, use this as the percentage base.  2) If auto-height,
+      // keep looking, unless the frame is positioned.
+      if (NS_AUTOHEIGHT == rs->ComputedHeight()) {
+        if (rs->mFrame->IsAbsolutelyPositioned()) {
+          break;
+        } else {
+          continue;
+        }
+      }
+    }
+    else if (nsGkAtoms::canvasFrame == frameType) {
+      // Always continue on to the height calculation
+    }
+    else if (nsGkAtoms::pageContentFrame == frameType) {
+      nsIFrame* prevInFlow = rs->mFrame->GetPrevInFlow();
+      // only use the page content frame for a height basis if it is the first in flow
+      if (prevInFlow) 
+        break;
+    }
+    else {
+      break;
+    }
+
+    // if the ancestor is the page content frame then the percent base is 
+    // the avail height, otherwise it is the computed height
+    result = (nsGkAtoms::pageContentFrame == frameType)
+             ? rs->AvailableHeight() : rs->ComputedHeight();
+    // if unconstrained - don't sutract borders - would result in huge height
+    if (NS_AUTOHEIGHT == result) return result;
+
+    // if we got to the canvas or page content frame, then subtract out 
+    // margin/border/padding for the BODY and HTML elements
+    if ((nsGkAtoms::canvasFrame == frameType) || 
+        (nsGkAtoms::pageContentFrame == frameType)) {
+
+      result -= GetBlockMarginBorderPadding(firstAncestorRI);
+      result -= GetBlockMarginBorderPadding(secondAncestorRI);
+
+#ifdef DEBUG
+      // make sure the first ancestor is the HTML and the second is the BODY
+      if (firstAncestorRI) {
+        nsIContent* frameContent = firstAncestorRI->mFrame->GetContent();
+        if (frameContent) {
+          NS_ASSERTION(frameContent->IsHTMLElement(nsGkAtoms::html),
+                       "First ancestor is not HTML");
+        }
+      }
+      if (secondAncestorRI) {
+        nsIContent* frameContent = secondAncestorRI->mFrame->GetContent();
+        if (frameContent) {
+          NS_ASSERTION(frameContent->IsHTMLElement(nsGkAtoms::body),
+                       "Second ancestor is not BODY");
+        }
+      }
+#endif
+      
+    }
+    // if we got to the html frame (a block child of the canvas) ...
+    else if (nsGkAtoms::blockFrame == frameType &&
+             rs->mParentReflowInput &&
+             nsGkAtoms::canvasFrame ==
+               rs->mParentReflowInput->mFrame->GetType()) {
+      // ... then subtract out margin/border/padding for the BODY element
+      result -= GetBlockMarginBorderPadding(secondAncestorRI);
+    }
+    break;
+  }
+
+  // Make sure not to return a negative height here!
+  return std::max(result, 0);
+}
+
+// Called by InitConstraints() to compute the containing block rectangle for
+// the element. Handles the special logic for absolutely positioned elements
+LogicalSize
+ReflowInput::ComputeContainingBlockRectangle(
+                     nsPresContext*           aPresContext,
+                     const ReflowInput* aContainingBlockRI) const
+{
+  // Unless the element is absolutely positioned, the containing block is
+  // formed by the content edge of the nearest block-level ancestor
+  LogicalSize cbSize = aContainingBlockRI->ComputedSize();
+
+  WritingMode wm = aContainingBlockRI->GetWritingMode();
+
+  // mFrameType for abs-pos tables is NS_CSS_FRAME_TYPE_BLOCK, so we need to
+  // special case them here.
+  if (NS_FRAME_GET_TYPE(mFrameType) == NS_CSS_FRAME_TYPE_ABSOLUTE ||
+      (mFrame->GetType() == nsGkAtoms::tableFrame &&
+       mFrame->IsAbsolutelyPositioned() &&
+       (mFrame->GetParent()->GetStateBits() & NS_FRAME_OUT_OF_FLOW))) {
+    // See if the ancestor is block-level or inline-level
+    if (NS_FRAME_GET_TYPE(aContainingBlockRI->mFrameType) == NS_CSS_FRAME_TYPE_INLINE) {
+      // Base our size on the actual size of the frame.  In cases when this is
+      // completely bogus (eg initial reflow), this code shouldn't even be
+      // called, since the code in nsInlineFrame::Reflow will pass in
+      // the containing block dimensions to our constructor.
+      // XXXbz we should be taking the in-flows into account too, but
+      // that's very hard.
+
+      LogicalMargin computedBorder =
+        aContainingBlockRI->ComputedLogicalBorderPadding() -
+        aContainingBlockRI->ComputedLogicalPadding();
+      cbSize.ISize(wm) = aContainingBlockRI->mFrame->ISize(wm) -
+                         computedBorder.IStartEnd(wm);
+      NS_ASSERTION(cbSize.ISize(wm) >= 0,
+                   "Negative containing block isize!");
+      cbSize.BSize(wm) = aContainingBlockRI->mFrame->BSize(wm) -
+                         computedBorder.BStartEnd(wm);
+      NS_ASSERTION(cbSize.BSize(wm) >= 0,
+                   "Negative containing block bsize!");
+    } else {
+      // If the ancestor is block-level, the containing block is formed by the
+      // padding edge of the ancestor
+      cbSize.ISize(wm) +=
+        aContainingBlockRI->ComputedLogicalPadding().IStartEnd(wm);
+      cbSize.BSize(wm) +=
+        aContainingBlockRI->ComputedLogicalPadding().BStartEnd(wm);
+    }
+  } else {
+    // an element in quirks mode gets a containing block based on looking for a
+    // parent with a non-auto height if the element has a percent height
+    // Note: We don't emulate this quirk for percents in calc() or in
+    // vertical writing modes.
+    if (!wm.IsVertical() &&
+        NS_AUTOHEIGHT == cbSize.BSize(wm)) {
+      if (eCompatibility_NavQuirks == aPresContext->CompatibilityMode() &&
+          mStylePosition->mHeight.GetUnit() == eStyleUnit_Percent) {
+        cbSize.BSize(wm) = CalcQuirkContainingBlockHeight(aContainingBlockRI);
+      }
+    }
+  }
+
+  return cbSize.ConvertTo(GetWritingMode(), wm);
+}
+
+static eNormalLineHeightControl GetNormalLineHeightCalcControl(void)
+{
+  if (sNormalLineHeightControl == eUninitialized) {
+    // browser.display.normal_lineheight_calc_control is not user
+    // changeable, so no need to register callback for it.
+    int32_t val =
+      Preferences::GetInt("browser.display.normal_lineheight_calc_control",
+                          eNoExternalLeading);
+    sNormalLineHeightControl = static_cast<eNormalLineHeightControl>(val);
+  }
+  return sNormalLineHeightControl;
+}
+
+static inline bool
+IsSideCaption(nsIFrame* aFrame, const nsStyleDisplay* aStyleDisplay,
+              WritingMode aWM)
+{
+  if (aStyleDisplay->mDisplay != StyleDisplay::TableCaption) {
+    return false;
+  }
+  uint8_t captionSide = aFrame->StyleTableBorder()->mCaptionSide;
+  return captionSide == NS_STYLE_CAPTION_SIDE_LEFT ||
+         captionSide == NS_STYLE_CAPTION_SIDE_RIGHT;
+}
+
+// Flex/grid items resolve block-axis percentage margin & padding against the
+// containing block block-size (also for abs/fixed-pos child frames).
+// For everything else: the CSS21 spec requires that margin and padding
+// percentage values are calculated with respect to the inline-size of the
+// containing block, even for margin & padding in the block axis.
+static LogicalSize
+OffsetPercentBasis(const nsIFrame*    aFrame,
+                   WritingMode        aWM,
+                   const LogicalSize& aContainingBlockSize)
+{
+  LogicalSize offsetPercentBasis = aContainingBlockSize;
+  if (MOZ_LIKELY(!aFrame->GetParent() ||
+                 !aFrame->GetParent()->IsFlexOrGridContainer())) {
+    offsetPercentBasis.BSize(aWM) = offsetPercentBasis.ISize(aWM);
+  } else if (offsetPercentBasis.BSize(aWM) == NS_AUTOHEIGHT) {
+    offsetPercentBasis.BSize(aWM) = 0;
+  }
+
+  return offsetPercentBasis;
+}
+
+// XXX refactor this code to have methods for each set of properties
+// we are computing: width,height,line-height; margin; offsets
+
+void
+ReflowInput::InitConstraints(nsPresContext*     aPresContext,
+                                   const LogicalSize& aContainingBlockSize,
+                                   const nsMargin*    aBorder,
+                                   const nsMargin*    aPadding,
+                                   nsIAtom*           aFrameType)
+{
+  WritingMode wm = GetWritingMode();
+  DISPLAY_INIT_CONSTRAINTS(mFrame, this,
+                           aContainingBlockSize.ISize(wm),
+                           aContainingBlockSize.BSize(wm),
+                           aBorder, aPadding);
+
+  // If this is a reflow root, then set the computed width and
+  // height equal to the available space
+  if (nullptr == mParentReflowInput || mFlags.mDummyParentReflowInput) {
+    // XXXldb This doesn't mean what it used to!
+    InitOffsets(wm, OffsetPercentBasis(mFrame, wm, aContainingBlockSize),
+                aFrameType, mFlags, aBorder, aPadding);
+    // Override mComputedMargin since reflow roots start from the
+    // frame's boundary, which is inside the margin.
+    ComputedPhysicalMargin().SizeTo(0, 0, 0, 0);
+    ComputedPhysicalOffsets().SizeTo(0, 0, 0, 0);
+
+    ComputedISize() =
+      AvailableISize() - ComputedLogicalBorderPadding().IStartEnd(wm);
+    if (ComputedISize() < 0) {
+      ComputedISize() = 0;
+    }
+    if (AvailableBSize() != NS_UNCONSTRAINEDSIZE) {
+      ComputedBSize() =
+        AvailableBSize() - ComputedLogicalBorderPadding().BStartEnd(wm);
+      if (ComputedBSize() < 0) {
+        ComputedBSize() = 0;
+      }
+    } else {
+      ComputedBSize() = NS_UNCONSTRAINEDSIZE;
+    }
+
+    ComputedMinWidth() = ComputedMinHeight() = 0;
+    ComputedMaxWidth() = ComputedMaxHeight() = NS_UNCONSTRAINEDSIZE;
+  } else {
+    // Get the containing block reflow state
+    const ReflowInput* cbrs = mCBReflowInput;
+    NS_ASSERTION(nullptr != cbrs, "no containing block");
+
+    // If we weren't given a containing block width and height, then
+    // compute one
+    LogicalSize cbSize = (aContainingBlockSize == LogicalSize(wm, -1, -1))
+      ? ComputeContainingBlockRectangle(aPresContext, cbrs)
+      : aContainingBlockSize;
+
+    // See if the containing block height is based on the size of its
+    // content
+    nsIAtom* fType;
+    if (NS_AUTOHEIGHT == cbSize.BSize(wm)) {
+      // See if the containing block is a cell frame which needs
+      // to use the mComputedHeight of the cell instead of what the cell block passed in.
+      // XXX It seems like this could lead to bugs with min-height and friends
+      if (cbrs->mParentReflowInput) {
+        fType = cbrs->mFrame->GetType();
+        if (IS_TABLE_CELL(fType)) {
+          // use the cell's computed block size
+          cbSize.BSize(wm) = cbrs->ComputedSize(wm).BSize(wm);
+        }
+      }
+    }
+
+    // XXX Might need to also pass the CB height (not width) for page boxes,
+    // too, if we implement them.
+
+    // For calculating positioning offsets, margins, borders and
+    // padding, we use the writing mode of the containing block
+    WritingMode cbwm = cbrs->GetWritingMode();
+    InitOffsets(cbwm, OffsetPercentBasis(mFrame, cbwm,
+                                         cbSize.ConvertTo(cbwm, wm)),
+                aFrameType, mFlags, aBorder, aPadding);
+
+    // For calculating the size of this box, we use its own writing mode
+    const nsStyleCoord &blockSize = mStylePosition->BSize(wm);
+    nsStyleUnit blockSizeUnit = blockSize.GetUnit();
+
+    // Check for a percentage based block size and a containing block
+    // block size that depends on the content block size
+    // XXX twiddling blockSizeUnit doesn't help anymore
+    // FIXME Shouldn't we fix that?
+    if (blockSize.HasPercent()) {
+      if (NS_AUTOHEIGHT == cbSize.BSize(wm)) {
+        // this if clause enables %-blockSize on replaced inline frames,
+        // such as images.  See bug 54119.  The else clause "blockSizeUnit = eStyleUnit_Auto;"
+        // used to be called exclusively.
+        if (NS_FRAME_REPLACED(NS_CSS_FRAME_TYPE_INLINE) == mFrameType ||
+            NS_FRAME_REPLACED_CONTAINS_BLOCK(
+                NS_CSS_FRAME_TYPE_INLINE) == mFrameType) {
+          // Get the containing block reflow state
+          NS_ASSERTION(nullptr != cbrs, "no containing block");
+          // in quirks mode, get the cb height using the special quirk method
+          if (!wm.IsVertical() &&
+              eCompatibility_NavQuirks == aPresContext->CompatibilityMode()) {
+            if (!IS_TABLE_CELL(fType)) {
+              cbSize.BSize(wm) = CalcQuirkContainingBlockHeight(cbrs);
+              if (cbSize.BSize(wm) == NS_AUTOHEIGHT) {
+                blockSizeUnit = eStyleUnit_Auto;
+              }
+            }
+            else {
+              blockSizeUnit = eStyleUnit_Auto;
+            }
+          }
+          // in standard mode, use the cb block size.  if it's "auto",
+          // as will be the case by default in BODY, use auto block size
+          // as per CSS2 spec.
+          else
+          {
+            nscoord computedBSize = cbrs->ComputedSize(wm).BSize(wm);
+            if (NS_AUTOHEIGHT != computedBSize) {
+              cbSize.BSize(wm) = computedBSize;
+            }
+            else {
+              blockSizeUnit = eStyleUnit_Auto;
+            }
+          }
+        }
+        else {
+          // default to interpreting the blockSize like 'auto'
+          blockSizeUnit = eStyleUnit_Auto;
+        }
+      }
+    }
+
+    // Compute our offsets if the element is relatively positioned.  We
+    // need the correct containing block inline-size and block-size
+    // here, which is why we need to do it after all the quirks-n-such
+    // above. (If the element is sticky positioned, we need to wait
+    // until the scroll container knows its size, so we compute offsets
+    // from StickyScrollContainer::UpdatePositions.)
+    if (mStyleDisplay->IsRelativelyPositioned(mFrame) &&
+        NS_STYLE_POSITION_RELATIVE == mStyleDisplay->mPosition) {
+      ComputeRelativeOffsets(cbwm, mFrame, cbSize.ConvertTo(cbwm, wm),
+                             ComputedPhysicalOffsets());
+    } else {
+      // Initialize offsets to 0
+      ComputedPhysicalOffsets().SizeTo(0, 0, 0, 0);
+    }
+
+    // Calculate the computed values for min and max properties.  Note that
+    // this MUST come after we've computed our border and padding.
+    ComputeMinMaxValues(cbSize);
+
+    // Calculate the computed inlineSize and blockSize.
+    // This varies by frame type.
+
+    if (NS_CSS_FRAME_TYPE_INTERNAL_TABLE == mFrameType) {
+      // Internal table elements. The rules vary depending on the type.
+      // Calculate the computed isize
+      bool rowOrRowGroup = false;
+      const nsStyleCoord &inlineSize = mStylePosition->ISize(wm);
+      nsStyleUnit inlineSizeUnit = inlineSize.GetUnit();
+      if ((StyleDisplay::TableRow == mStyleDisplay->mDisplay) ||
+          (StyleDisplay::TableRowGroup == mStyleDisplay->mDisplay)) {
+        // 'inlineSize' property doesn't apply to table rows and row groups
+        inlineSizeUnit = eStyleUnit_Auto;
+        rowOrRowGroup = true;
+      }
+
+      // calc() with percentages acts like auto on internal table elements
+      if (eStyleUnit_Auto == inlineSizeUnit ||
+          (inlineSize.IsCalcUnit() && inlineSize.CalcHasPercent())) {
+        ComputedISize() = AvailableISize();
+
+        if ((ComputedISize() != NS_UNCONSTRAINEDSIZE) && !rowOrRowGroup){
+          // Internal table elements don't have margins. Only tables and
+          // cells have border and padding
+          ComputedISize() -= ComputedLogicalBorderPadding().IStartEnd(wm);
+          if (ComputedISize() < 0)
+            ComputedISize() = 0;
+        }
+        NS_ASSERTION(ComputedISize() >= 0, "Bogus computed isize");
+
+      } else {
+        NS_ASSERTION(inlineSizeUnit == inlineSize.GetUnit(),
+                     "unexpected inline size unit change");
+        ComputedISize() = ComputeISizeValue(cbSize.ISize(wm),
+                                            mStylePosition->mBoxSizing,
+                                            inlineSize);
+      }
+
+      // Calculate the computed block size
+      if ((StyleDisplay::TableColumn == mStyleDisplay->mDisplay) ||
+          (StyleDisplay::TableColumnGroup == mStyleDisplay->mDisplay)) {
+        // 'blockSize' property doesn't apply to table columns and column groups
+        blockSizeUnit = eStyleUnit_Auto;
+      }
+      // calc() with percentages acts like 'auto' on internal table elements
+      if (eStyleUnit_Auto == blockSizeUnit ||
+          (blockSize.IsCalcUnit() && blockSize.CalcHasPercent())) {
+        ComputedBSize() = NS_AUTOHEIGHT;
+      } else {
+        NS_ASSERTION(blockSizeUnit == blockSize.GetUnit(),
+                     "unexpected block size unit change");
+        ComputedBSize() = ComputeBSizeValue(cbSize.BSize(wm),
+                                            mStylePosition->mBoxSizing,
+                                            blockSize);
+      }
+
+      // Doesn't apply to table elements
+      ComputedMinWidth() = ComputedMinHeight() = 0;
+      ComputedMaxWidth() = ComputedMaxHeight() = NS_UNCONSTRAINEDSIZE;
+
+    } else if (NS_FRAME_GET_TYPE(mFrameType) == NS_CSS_FRAME_TYPE_ABSOLUTE) {
+      // XXX not sure if this belongs here or somewhere else - cwk
+      InitAbsoluteConstraints(aPresContext, cbrs, cbSize.ConvertTo(cbrs->GetWritingMode(), wm), aFrameType);
+    } else {
+      AutoMaybeDisableFontInflation an(mFrame);
+
+      bool isBlock = NS_CSS_FRAME_TYPE_BLOCK == NS_FRAME_GET_TYPE(mFrameType);
+      typedef nsIFrame::ComputeSizeFlags ComputeSizeFlags;
+      ComputeSizeFlags computeSizeFlags =
+        isBlock ? ComputeSizeFlags::eDefault : ComputeSizeFlags::eShrinkWrap;
+      if (mFlags.mIClampMarginBoxMinSize) {
+        computeSizeFlags = ComputeSizeFlags(computeSizeFlags |
+                             ComputeSizeFlags::eIClampMarginBoxMinSize);
+      }
+      if (mFlags.mBClampMarginBoxMinSize) {
+        computeSizeFlags = ComputeSizeFlags(computeSizeFlags |
+                             ComputeSizeFlags::eBClampMarginBoxMinSize);
+      }
+      if (mFlags.mShrinkWrap) {
+        computeSizeFlags =
+          ComputeSizeFlags(computeSizeFlags | ComputeSizeFlags::eShrinkWrap);
+      }
+      if (mFlags.mUseAutoBSize) {
+        computeSizeFlags =
+          ComputeSizeFlags(computeSizeFlags | ComputeSizeFlags::eUseAutoBSize);
+      }
+
+      nsIFrame* alignCB = mFrame->GetParent();
+      nsIAtom* alignCBType = alignCB ? alignCB->GetType() : nullptr;
+      if (alignCBType == nsGkAtoms::tableWrapperFrame &&
+          alignCB->GetParent()) {
+        auto parentCBType = alignCB->GetParent()->GetType();
+        // XXX grid-specific for now; maybe remove this check after we address bug 799725
+        if (parentCBType == nsGkAtoms::gridContainerFrame) {
+          alignCB = alignCB->GetParent();
+          alignCBType = parentCBType;
+        }
+      }
+      if (alignCBType == nsGkAtoms::gridContainerFrame) {
+        // Shrink-wrap grid items that will be aligned (rather than stretched)
+        // in its inline axis.
+        auto inlineAxisAlignment = wm.IsOrthogonalTo(cbwm) ?
+          mStylePosition->UsedAlignSelf(mFrame->StyleContext()->GetParent()) :
+          mStylePosition->UsedJustifySelf(mFrame->StyleContext()->GetParent());
+        if ((inlineAxisAlignment != NS_STYLE_ALIGN_STRETCH &&
+             inlineAxisAlignment != NS_STYLE_ALIGN_NORMAL) ||
+            mStyleMargin->mMargin.GetIStartUnit(wm) == eStyleUnit_Auto ||
+            mStyleMargin->mMargin.GetIEndUnit(wm) == eStyleUnit_Auto) {
+          computeSizeFlags =
+            ComputeSizeFlags(computeSizeFlags | ComputeSizeFlags::eShrinkWrap);
+        }
+      } else {
+        // Make sure legend frames with display:block and width:auto still
+        // shrink-wrap.
+        // Also shrink-wrap blocks that are orthogonal to their container.
+        if (isBlock &&
+            ((aFrameType == nsGkAtoms::legendFrame &&
+              mFrame->StyleContext()->GetPseudo() != nsCSSAnonBoxes::scrolledContent) ||
+             (aFrameType == nsGkAtoms::scrollFrame &&
+              mFrame->GetContentInsertionFrame()->GetType() == nsGkAtoms::legendFrame) ||
+             (mCBReflowInput &&
+              mCBReflowInput->GetWritingMode().IsOrthogonalTo(mWritingMode)))) {
+          computeSizeFlags =
+            ComputeSizeFlags(computeSizeFlags | ComputeSizeFlags::eShrinkWrap);
+        }
+
+        if (alignCBType == nsGkAtoms::flexContainerFrame) {
+          computeSizeFlags =
+            ComputeSizeFlags(computeSizeFlags | ComputeSizeFlags::eShrinkWrap);
+
+          // If we're inside of a flex container that needs to measure our
+          // auto height, pass that information along to ComputeSize().
+          if (mFlags.mIsFlexContainerMeasuringHeight) {
+            computeSizeFlags =
+              ComputeSizeFlags(computeSizeFlags | ComputeSizeFlags::eUseAutoBSize);
+          }
+        } else {
+          MOZ_ASSERT(!mFlags.mIsFlexContainerMeasuringHeight,
+                     "We're not in a flex container, so the flag "
+                     "'mIsFlexContainerMeasuringHeight' shouldn't be set");
+        }
+      }
+
+      if (cbSize.ISize(wm) == NS_UNCONSTRAINEDSIZE) {
+        // For orthogonal flows, where we found a parent orthogonal-limit
+        // for AvailableISize() in Init(), we'll use the same here as well.
+        cbSize.ISize(wm) = AvailableISize();
+      }
+
+      LogicalSize size =
+        mFrame->ComputeSize(mRenderingContext, wm, cbSize, AvailableISize(),
+                           ComputedLogicalMargin().Size(wm),
+                           ComputedLogicalBorderPadding().Size(wm) -
+                             ComputedLogicalPadding().Size(wm),
+                           ComputedLogicalPadding().Size(wm),
+                           computeSizeFlags);
+
+      ComputedISize() = size.ISize(wm);
+      ComputedBSize() = size.BSize(wm);
+      NS_ASSERTION(ComputedISize() >= 0, "Bogus inline-size");
+      NS_ASSERTION(ComputedBSize() == NS_UNCONSTRAINEDSIZE ||
+                   ComputedBSize() >= 0, "Bogus block-size");
+
+      // Exclude inline tables, side captions, flex and grid items from block
+      // margin calculations.
+      if (isBlock &&
+          !IsSideCaption(mFrame, mStyleDisplay, cbwm) &&
+          mStyleDisplay->mDisplay != StyleDisplay::InlineTable &&
+          alignCBType != nsGkAtoms::flexContainerFrame &&
+          alignCBType != nsGkAtoms::gridContainerFrame) {
+        CalculateBlockSideMargins(aFrameType);
+      }
+    }
+  }
+}
+
+static void
+UpdateProp(FrameProperties& aProps,
+           const FramePropertyDescriptor<nsMargin>* aProperty,
+           bool aNeeded,
+           nsMargin& aNewValue)
+{
+  if (aNeeded) {
+    nsMargin* propValue = aProps.Get(aProperty);
+    if (propValue) {
+      *propValue = aNewValue;
+    } else {
+      aProps.Set(aProperty, new nsMargin(aNewValue));
+    }
+  } else {
+    aProps.Delete(aProperty);
+  }
+}
+
+void
+SizeComputationInput::InitOffsets(WritingMode aWM,
+                              const LogicalSize& aPercentBasis,
+                              nsIAtom* aFrameType,
+                              ReflowInputFlags aFlags,
+                              const nsMargin* aBorder,
+                              const nsMargin* aPadding)
+{
+  DISPLAY_INIT_OFFSETS(mFrame, this, aPercentBasis, aBorder, aPadding);
+
+  // Since we are in reflow, we don't need to store these properties anymore
+  // unless they are dependent on width, in which case we store the new value.
+  nsPresContext *presContext = mFrame->PresContext();
+  FrameProperties props(presContext->PropertyTable(), mFrame);
+  props.Delete(nsIFrame::UsedBorderProperty());
+
+  // Compute margins from the specified margin style information. These
+  // become the default computed values, and may be adjusted below
+  // XXX fix to provide 0,0 for the top&bottom margins for
+  // inline-non-replaced elements
+  bool needMarginProp = ComputeMargin(aWM, aPercentBasis);
+  // XXX We need to include 'auto' horizontal margins in this too!
+  // ... but if we did that, we'd need to fix nsFrame::GetUsedMargin
+  // to use it even when the margins are all zero (since sometimes
+  // they get treated as auto)
+  ::UpdateProp(props, nsIFrame::UsedMarginProperty(), needMarginProp,
+               ComputedPhysicalMargin());
+
+
+  const nsStyleDisplay *disp = mFrame->StyleDisplay();
+  bool isThemed = mFrame->IsThemed(disp);
+  bool needPaddingProp;
+  nsIntMargin widget;
+  if (isThemed &&
+      presContext->GetTheme()->GetWidgetPadding(presContext->DeviceContext(),
+                                                mFrame, disp->mAppearance,
+                                                &widget)) {
+    ComputedPhysicalPadding().top = presContext->DevPixelsToAppUnits(widget.top);
+    ComputedPhysicalPadding().right = presContext->DevPixelsToAppUnits(widget.right);
+    ComputedPhysicalPadding().bottom = presContext->DevPixelsToAppUnits(widget.bottom);
+    ComputedPhysicalPadding().left = presContext->DevPixelsToAppUnits(widget.left);
+    needPaddingProp = false;
+  }
+  else if (mFrame->IsSVGText()) {
+    ComputedPhysicalPadding().SizeTo(0, 0, 0, 0);
+    needPaddingProp = false;
+  }
+  else if (aPadding) { // padding is an input arg
+    ComputedPhysicalPadding() = *aPadding;
+    needPaddingProp = mFrame->StylePadding()->IsWidthDependent() ||
+	  (mFrame->GetStateBits() & NS_FRAME_REFLOW_ROOT);
+  }
+  else {
+    needPaddingProp = ComputePadding(aWM, aPercentBasis, aFrameType);
+  }
+
+  // Add [align|justify]-content:baseline padding contribution.
+  typedef const FramePropertyDescriptor<SmallValueHolder<nscoord>>* Prop;
+  auto ApplyBaselinePadding = [this, &needPaddingProp]
+         (LogicalAxis aAxis, Prop aProp) {
+    bool found;
+    nscoord val = mFrame->Properties().Get(aProp, &found);
+    if (found) {
+      NS_ASSERTION(val != nscoord(0), "zero in this property is useless");
+      WritingMode wm = GetWritingMode();
+      LogicalSide side;
+      if (val > 0) {
+        side = MakeLogicalSide(aAxis, eLogicalEdgeStart);
+      } else {
+        side = MakeLogicalSide(aAxis, eLogicalEdgeEnd);
+        val = -val;
+      }
+      mComputedPadding.Side(wm.PhysicalSide(side)) += val;
+      needPaddingProp = true;
+    }
+  };
+  if (!aFlags.mUseAutoBSize) {
+    ApplyBaselinePadding(eLogicalAxisBlock, nsIFrame::BBaselinePadProperty());
+  }
+  if (!aFlags.mShrinkWrap) {
+    ApplyBaselinePadding(eLogicalAxisInline, nsIFrame::IBaselinePadProperty());
+  }
+
+  if (isThemed) {
+    nsIntMargin widget;
+    presContext->GetTheme()->GetWidgetBorder(presContext->DeviceContext(),
+                                             mFrame, disp->mAppearance,
+                                             &widget);
+    ComputedPhysicalBorderPadding().top =
+      presContext->DevPixelsToAppUnits(widget.top);
+    ComputedPhysicalBorderPadding().right =
+      presContext->DevPixelsToAppUnits(widget.right);
+    ComputedPhysicalBorderPadding().bottom =
+      presContext->DevPixelsToAppUnits(widget.bottom);
+    ComputedPhysicalBorderPadding().left =
+      presContext->DevPixelsToAppUnits(widget.left);
+  }
+  else if (mFrame->IsSVGText()) {
+    ComputedPhysicalBorderPadding().SizeTo(0, 0, 0, 0);
+  }
+  else if (aBorder) {  // border is an input arg
+    ComputedPhysicalBorderPadding() = *aBorder;
+  }
+  else {
+    ComputedPhysicalBorderPadding() = mFrame->StyleBorder()->GetComputedBorder();
+  }
+  ComputedPhysicalBorderPadding() += ComputedPhysicalPadding();
+
+  if (aFrameType == nsGkAtoms::tableFrame) {
+    nsTableFrame *tableFrame = static_cast<nsTableFrame*>(mFrame);
+
+    if (tableFrame->IsBorderCollapse()) {
+      // border-collapsed tables don't use any of their padding, and
+      // only part of their border.  We need to do this here before we
+      // try to do anything like handling 'auto' widths,
+      // 'box-sizing', or 'auto' margins.
+      ComputedPhysicalPadding().SizeTo(0,0,0,0);
+      SetComputedLogicalBorderPadding(
+        tableFrame->GetIncludedOuterBCBorder(mWritingMode));
+    }
+
+    // The margin is inherited to the table wrapper frame via
+    // the ::-moz-table-wrapper rule in ua.css.
+    ComputedPhysicalMargin().SizeTo(0, 0, 0, 0);
+  } else if (aFrameType == nsGkAtoms::scrollbarFrame) {
+    // scrollbars may have had their width or height smashed to zero
+    // by the associated scrollframe, in which case we must not report
+    // any padding or border.
+    nsSize size(mFrame->GetSize());
+    if (size.width == 0 || size.height == 0) {
+      ComputedPhysicalPadding().SizeTo(0,0,0,0);
+      ComputedPhysicalBorderPadding().SizeTo(0,0,0,0);
+    }
+  }
+  ::UpdateProp(props, nsIFrame::UsedPaddingProperty(), needPaddingProp,
+               ComputedPhysicalPadding());
+}
+
+// This code enforces section 10.3.3 of the CSS2 spec for this formula:
+//
+// 'margin-left' + 'border-left-width' + 'padding-left' + 'width' +
+//   'padding-right' + 'border-right-width' + 'margin-right'
+//   = width of containing block 
+//
+// Note: the width unit is not auto when this is called
+void
+ReflowInput::CalculateBlockSideMargins(nsIAtom* aFrameType)
+{
+  // Calculations here are done in the containing block's writing mode,
+  // which is where margins will eventually be applied: we're calculating
+  // margins that will be used by the container in its inline direction,
+  // which in the case of an orthogonal contained block will correspond to
+  // the block direction of this reflow state. So in the orthogonal-flow
+  // case, "CalculateBlock*Side*Margins" will actually end up adjusting
+  // the BStart/BEnd margins; those are the "sides" of the block from its
+  // container's point of view.
+  WritingMode cbWM =
+    mCBReflowInput ? mCBReflowInput->GetWritingMode(): GetWritingMode();
+
+  nscoord availISizeCBWM = AvailableSize(cbWM).ISize(cbWM);
+  nscoord computedISizeCBWM = ComputedSize(cbWM).ISize(cbWM);
+  if (computedISizeCBWM == NS_UNCONSTRAINEDSIZE) {
+    // For orthogonal flows, where we found a parent orthogonal-limit
+    // for AvailableISize() in Init(), we'll use the same here as well.
+    computedISizeCBWM = availISizeCBWM;
+  }
+
+  LAYOUT_WARN_IF_FALSE(NS_UNCONSTRAINEDSIZE != computedISizeCBWM &&
+                       NS_UNCONSTRAINEDSIZE != availISizeCBWM,
+                       "have unconstrained inline-size; this should only "
+                       "result from very large sizes, not attempts at "
+                       "intrinsic inline-size calculation");
+
+  LogicalMargin margin =
+    ComputedLogicalMargin().ConvertTo(cbWM, mWritingMode);
+  LogicalMargin borderPadding =
+    ComputedLogicalBorderPadding().ConvertTo(cbWM, mWritingMode);
+  nscoord sum = margin.IStartEnd(cbWM) +
+    borderPadding.IStartEnd(cbWM) + computedISizeCBWM;
+  if (sum == availISizeCBWM) {
+    // The sum is already correct
+    return;
+  }
+
+  // Determine the start and end margin values. The isize value
+  // remains constant while we do this.
+
+  // Calculate how much space is available for margins
+  nscoord availMarginSpace = availISizeCBWM - sum;
+
+  // If the available margin space is negative, then don't follow the
+  // usual overconstraint rules.
+  if (availMarginSpace < 0) {
+    margin.IEnd(cbWM) += availMarginSpace;
+    SetComputedLogicalMargin(margin.ConvertTo(mWritingMode, cbWM));
+    return;
+  }
+
+  // The css2 spec clearly defines how block elements should behave
+  // in section 10.3.3.
+  const nsStyleSides& styleSides = mStyleMargin->mMargin;
+  bool isAutoStartMargin = eStyleUnit_Auto == styleSides.GetIStartUnit(cbWM);
+  bool isAutoEndMargin = eStyleUnit_Auto == styleSides.GetIEndUnit(cbWM);
+  if (!isAutoStartMargin && !isAutoEndMargin) {
+    // Neither margin is 'auto' so we're over constrained. Use the
+    // 'direction' property of the parent to tell which margin to
+    // ignore
+    // First check if there is an HTML alignment that we should honor
+    const ReflowInput* prs = mParentReflowInput;
+    if (aFrameType == nsGkAtoms::tableFrame) {
+      NS_ASSERTION(prs->mFrame->GetType() == nsGkAtoms::tableWrapperFrame,
+                   "table not inside table wrapper");
+      // Center the table within the table wrapper based on the alignment
+      // of the table wrapper's parent.
+      prs = prs->mParentReflowInput;
+    }
+    if (prs &&
+        (prs->mStyleText->mTextAlign == NS_STYLE_TEXT_ALIGN_MOZ_LEFT ||
+         prs->mStyleText->mTextAlign == NS_STYLE_TEXT_ALIGN_MOZ_CENTER ||
+         prs->mStyleText->mTextAlign == NS_STYLE_TEXT_ALIGN_MOZ_RIGHT)) {
+      if (prs->mWritingMode.IsBidiLTR()) {
+        isAutoStartMargin =
+          prs->mStyleText->mTextAlign != NS_STYLE_TEXT_ALIGN_MOZ_LEFT;
+        isAutoEndMargin =
+          prs->mStyleText->mTextAlign != NS_STYLE_TEXT_ALIGN_MOZ_RIGHT;
+      } else {
+        isAutoStartMargin =
+          prs->mStyleText->mTextAlign != NS_STYLE_TEXT_ALIGN_MOZ_RIGHT;
+        isAutoEndMargin =
+          prs->mStyleText->mTextAlign != NS_STYLE_TEXT_ALIGN_MOZ_LEFT;
+      }
+    }
+    // Otherwise apply the CSS rules, and ignore one margin by forcing
+    // it to 'auto', depending on 'direction'.
+    else {
+      isAutoEndMargin = true;
+    }
+  }
+
+  // Logic which is common to blocks and tables
+  // The computed margins need not be zero because the 'auto' could come from
+  // overconstraint or from HTML alignment so values need to be accumulated
+
+  if (isAutoStartMargin) {
+    if (isAutoEndMargin) {
+      // Both margins are 'auto' so the computed addition should be equal
+      nscoord forStart = availMarginSpace / 2;
+      margin.IStart(cbWM) += forStart;
+      margin.IEnd(cbWM) += availMarginSpace - forStart;
+    } else {
+      margin.IStart(cbWM) += availMarginSpace;
+    }
+  } else if (isAutoEndMargin) {
+    margin.IEnd(cbWM) += availMarginSpace;
+  }
+  SetComputedLogicalMargin(margin.ConvertTo(mWritingMode, cbWM));
+}
+
+#define NORMAL_LINE_HEIGHT_FACTOR 1.2f    // in term of emHeight 
+// For "normal" we use the font's normal line height (em height + leading).
+// If both internal leading and  external leading specified by font itself
+// are zeros, we should compensate this by creating extra (external) leading 
+// in eCompensateLeading mode. This is necessary because without this 
+// compensation, normal line height might looks too tight. 
+
+// For risk management, we use preference to control the behavior, and 
+// eNoExternalLeading is the old behavior.
+static nscoord
+GetNormalLineHeight(nsFontMetrics* aFontMetrics)
+{
+  NS_PRECONDITION(nullptr != aFontMetrics, "no font metrics");
+
+  nscoord normalLineHeight;
+
+  nscoord externalLeading = aFontMetrics->ExternalLeading();
+  nscoord internalLeading = aFontMetrics->InternalLeading();
+  nscoord emHeight = aFontMetrics->EmHeight();
+  switch (GetNormalLineHeightCalcControl()) {
+  case eIncludeExternalLeading:
+    normalLineHeight = emHeight+ internalLeading + externalLeading;
+    break;
+  case eCompensateLeading:
+    if (!internalLeading && !externalLeading)
+      normalLineHeight = NSToCoordRound(emHeight * NORMAL_LINE_HEIGHT_FACTOR);
+    else
+      normalLineHeight = emHeight+ internalLeading + externalLeading;
+    break;
+  default:
+    //case eNoExternalLeading:
+    normalLineHeight = emHeight + internalLeading;
+  }
+  return normalLineHeight;
+}
+
+static inline nscoord
+ComputeLineHeight(nsStyleContext* aStyleContext,
+                  nscoord aBlockBSize,
+                  float aFontSizeInflation)
+{
+  const nsStyleCoord& lhCoord = aStyleContext->StyleText()->mLineHeight;
+
+  if (lhCoord.GetUnit() == eStyleUnit_Coord) {
+    nscoord result = lhCoord.GetCoordValue();
+    if (aFontSizeInflation != 1.0f) {
+      result = NSToCoordRound(result * aFontSizeInflation);
+    }
+    return result;
+  }
+
+  if (lhCoord.GetUnit() == eStyleUnit_Factor)
+    // For factor units the computed value of the line-height property 
+    // is found by multiplying the factor by the font's computed size
+    // (adjusted for min-size prefs and text zoom).
+    return NSToCoordRound(lhCoord.GetFactorValue() * aFontSizeInflation *
+                          aStyleContext->StyleFont()->mFont.size);
+
+  NS_ASSERTION(lhCoord.GetUnit() == eStyleUnit_Normal ||
+               lhCoord.GetUnit() == eStyleUnit_Enumerated,
+               "bad line-height unit");
+  
+  if (lhCoord.GetUnit() == eStyleUnit_Enumerated) {
+    NS_ASSERTION(lhCoord.GetIntValue() == NS_STYLE_LINE_HEIGHT_BLOCK_HEIGHT,
+                 "bad line-height value");
+    if (aBlockBSize != NS_AUTOHEIGHT) {
+      return aBlockBSize;
+    }
+  }
+
+  RefPtr<nsFontMetrics> fm = nsLayoutUtils::
+    GetFontMetricsForStyleContext(aStyleContext, aFontSizeInflation);
+  return GetNormalLineHeight(fm);
+}
+
+nscoord
+ReflowInput::CalcLineHeight() const
+{
+  nscoord blockBSize =
+    nsLayoutUtils::IsNonWrapperBlock(mFrame) ? ComputedBSize() :
+    (mCBReflowInput ? mCBReflowInput->ComputedBSize() : NS_AUTOHEIGHT);
+
+  return CalcLineHeight(mFrame->GetContent(), mFrame->StyleContext(), blockBSize,
+                        nsLayoutUtils::FontSizeInflationFor(mFrame));
+}
+
+/* static */ nscoord
+ReflowInput::CalcLineHeight(nsIContent* aContent,
+                                  nsStyleContext* aStyleContext,
+                                  nscoord aBlockBSize,
+                                  float aFontSizeInflation)
+{
+  NS_PRECONDITION(aStyleContext, "Must have a style context");
+
+  nscoord lineHeight =
+    ComputeLineHeight(aStyleContext, aBlockBSize, aFontSizeInflation);
+
+  NS_ASSERTION(lineHeight >= 0, "ComputeLineHeight screwed up");
+
+  HTMLInputElement* input = HTMLInputElement::FromContentOrNull(aContent);
+  if (input && input->IsSingleLineTextControl()) {
+    // For Web-compatibility, single-line text input elements cannot
+    // have a line-height smaller than one.
+    nscoord lineHeightOne =
+      aFontSizeInflation * aStyleContext->StyleFont()->mFont.size;
+    if (lineHeight < lineHeightOne) {
+      lineHeight = lineHeightOne;
+    }
+  }
+
+  return lineHeight;
+}
+
+bool
+SizeComputationInput::ComputeMargin(WritingMode aWM,
+                                const LogicalSize& aPercentBasis)
+{
+  // SVG text frames have no margin.
+  if (mFrame->IsSVGText()) {
+    return false;
+  }
+
+  // If style style can provide us the margin directly, then use it.
+  const nsStyleMargin *styleMargin = mFrame->StyleMargin();
+
+  bool isCBDependent = !styleMargin->GetMargin(ComputedPhysicalMargin());
+  if (isCBDependent) {
+    // We have to compute the value. Note that this calculation is
+    // performed according to the writing mode of the containing block
+    // (http://dev.w3.org/csswg/css-writing-modes-3/#orthogonal-flows)
+    LogicalMargin m(aWM);
+    m.IStart(aWM) = nsLayoutUtils::
+      ComputeCBDependentValue(aPercentBasis.ISize(aWM),
+                              styleMargin->mMargin.GetIStart(aWM));
+    m.IEnd(aWM) = nsLayoutUtils::
+      ComputeCBDependentValue(aPercentBasis.ISize(aWM),
+                              styleMargin->mMargin.GetIEnd(aWM));
+
+    m.BStart(aWM) = nsLayoutUtils::
+      ComputeCBDependentValue(aPercentBasis.BSize(aWM),
+                              styleMargin->mMargin.GetBStart(aWM));
+    m.BEnd(aWM) = nsLayoutUtils::
+      ComputeCBDependentValue(aPercentBasis.BSize(aWM),
+                              styleMargin->mMargin.GetBEnd(aWM));
+
+    SetComputedLogicalMargin(aWM, m);
+  }
+
+  // ... but font-size-inflation-based margin adjustment uses the
+  // frame's writing mode
+  nscoord marginAdjustment = FontSizeInflationListMarginAdjustment(mFrame);
+
+  if (marginAdjustment > 0) {
+    LogicalMargin m = ComputedLogicalMargin();
+    m.IStart(mWritingMode) += marginAdjustment;
+    SetComputedLogicalMargin(m);
+  }
+
+  return isCBDependent;
+}
+
+bool
+SizeComputationInput::ComputePadding(WritingMode aWM,
+                                 const LogicalSize& aPercentBasis,
+                                 nsIAtom* aFrameType)
+{
+  // If style can provide us the padding directly, then use it.
+  const nsStylePadding *stylePadding = mFrame->StylePadding();
+  bool isCBDependent = !stylePadding->GetPadding(ComputedPhysicalPadding());
+  // a table row/col group, row/col doesn't have padding
+  // XXXldb Neither do border-collapse tables.
+  if (nsGkAtoms::tableRowGroupFrame == aFrameType ||
+      nsGkAtoms::tableColGroupFrame == aFrameType ||
+      nsGkAtoms::tableRowFrame      == aFrameType ||
+      nsGkAtoms::tableColFrame      == aFrameType) {
+    ComputedPhysicalPadding().SizeTo(0,0,0,0);
+  }
+  else if (isCBDependent) {
+    // We have to compute the value. This calculation is performed
+    // according to the writing mode of the containing block
+    // (http://dev.w3.org/csswg/css-writing-modes-3/#orthogonal-flows)
+    // clamp negative calc() results to 0
+    LogicalMargin p(aWM);
+    p.IStart(aWM) = std::max(0, nsLayoutUtils::
+      ComputeCBDependentValue(aPercentBasis.ISize(aWM),
+                              stylePadding->mPadding.GetIStart(aWM)));
+    p.IEnd(aWM) = std::max(0, nsLayoutUtils::
+      ComputeCBDependentValue(aPercentBasis.ISize(aWM),
+                              stylePadding->mPadding.GetIEnd(aWM)));
+
+    p.BStart(aWM) = std::max(0, nsLayoutUtils::
+      ComputeCBDependentValue(aPercentBasis.BSize(aWM),
+                              stylePadding->mPadding.GetBStart(aWM)));
+    p.BEnd(aWM) = std::max(0, nsLayoutUtils::
+      ComputeCBDependentValue(aPercentBasis.BSize(aWM),
+                              stylePadding->mPadding.GetBEnd(aWM)));
+
+    SetComputedLogicalPadding(aWM, p);
+  }
+  return isCBDependent;
+}
+
+void
+ReflowInput::ComputeMinMaxValues(const LogicalSize&aCBSize)
+{
+  WritingMode wm = GetWritingMode();
+
+  const nsStyleCoord& minISize = mStylePosition->MinISize(wm);
+  const nsStyleCoord& maxISize = mStylePosition->MaxISize(wm);
+  const nsStyleCoord& minBSize = mStylePosition->MinBSize(wm);
+  const nsStyleCoord& maxBSize = mStylePosition->MaxBSize(wm);
+
+  // NOTE: min-width:auto resolves to 0, except on a flex item. (But
+  // even there, it's supposed to be ignored (i.e. treated as 0) until
+  // the flex container explicitly resolves & considers it.)
+  if (eStyleUnit_Auto == minISize.GetUnit()) {
+    ComputedMinISize() = 0;
+  } else {
+    ComputedMinISize() = ComputeISizeValue(aCBSize.ISize(wm),
+                                           mStylePosition->mBoxSizing,
+                                           minISize);
+  }
+
+  if (eStyleUnit_None == maxISize.GetUnit()) {
+    // Specified value of 'none'
+    ComputedMaxISize() = NS_UNCONSTRAINEDSIZE;  // no limit
+  } else {
+    ComputedMaxISize() = ComputeISizeValue(aCBSize.ISize(wm),
+                                           mStylePosition->mBoxSizing,
+                                           maxISize);
+  }
+
+  // If the computed value of 'min-width' is greater than the value of
+  // 'max-width', 'max-width' is set to the value of 'min-width'
+  if (ComputedMinISize() > ComputedMaxISize()) {
+    ComputedMaxISize() = ComputedMinISize();
+  }
+
+  // Check for percentage based values and a containing block height that
+  // depends on the content height. Treat them like 'auto'
+  // Likewise, check for calc() with percentages on internal table elements;
+  // that's treated as 'auto' too.
+  // Likewise, if we're a child of a flex container who's measuring our
+  // intrinsic height, then we want to disregard our min-height.
+
+  // NOTE: min-height:auto resolves to 0, except on a flex item. (But
+  // even there, it's supposed to be ignored (i.e. treated as 0) until
+  // the flex container explicitly resolves & considers it.)
+  if (eStyleUnit_Auto == minBSize.GetUnit() ||
+      (NS_AUTOHEIGHT == aCBSize.BSize(wm) &&
+       minBSize.HasPercent()) ||
+      (mFrameType == NS_CSS_FRAME_TYPE_INTERNAL_TABLE &&
+       minBSize.IsCalcUnit() && minBSize.CalcHasPercent()) ||
+      mFlags.mIsFlexContainerMeasuringHeight) {
+    ComputedMinBSize() = 0;
+  } else {
+    ComputedMinBSize() = ComputeBSizeValue(aCBSize.BSize(wm),
+                                           mStylePosition->mBoxSizing,
+                                           minBSize);
+  }
+  nsStyleUnit maxBSizeUnit = maxBSize.GetUnit();
+  if (eStyleUnit_None == maxBSizeUnit) {
+    // Specified value of 'none'
+    ComputedMaxBSize() = NS_UNCONSTRAINEDSIZE;  // no limit
+  } else {
+    // Check for percentage based values and a containing block height that
+    // depends on the content height. Treat them like 'none'
+    // Likewise, check for calc() with percentages on internal table elements;
+    // that's treated as 'auto' too.
+    // Likewise, if we're a child of a flex container who's measuring our
+    // intrinsic height, then we want to disregard our max-height.
+    if ((NS_AUTOHEIGHT == aCBSize.BSize(wm) &&
+         maxBSize.HasPercent()) ||
+        (mFrameType == NS_CSS_FRAME_TYPE_INTERNAL_TABLE &&
+         maxBSize.IsCalcUnit() && maxBSize.CalcHasPercent()) ||
+        mFlags.mIsFlexContainerMeasuringHeight) {
+      ComputedMaxBSize() = NS_UNCONSTRAINEDSIZE;
+    } else {
+      ComputedMaxBSize() = ComputeBSizeValue(aCBSize.BSize(wm),
+                                             mStylePosition->mBoxSizing,
+                                             maxBSize);
+    }
+  }
+
+  // If the computed value of 'min-height' is greater than the value of
+  // 'max-height', 'max-height' is set to the value of 'min-height'
+  if (ComputedMinBSize() > ComputedMaxBSize()) {
+    ComputedMaxBSize() = ComputedMinBSize();
+  }
+}
+
+void
+ReflowInput::SetTruncated(const ReflowOutput& aMetrics,
+                                nsReflowStatus* aStatus) const
+{
+  const WritingMode containerWM = aMetrics.GetWritingMode();
+  if (GetWritingMode().IsOrthogonalTo(containerWM)) {
+    // Orthogonal flows are always reflowed with an unconstrained dimension,
+    // so should never end up truncated (see ReflowInput::Init()).
+    *aStatus &= ~NS_FRAME_TRUNCATED;
+  } else if (AvailableBSize() != NS_UNCONSTRAINEDSIZE &&
+             AvailableBSize() < aMetrics.BSize(containerWM) &&
+             !mFlags.mIsTopOfPage) {
+    *aStatus |= NS_FRAME_TRUNCATED;
+  } else {
+    *aStatus &= ~NS_FRAME_TRUNCATED;
+  }
+}
+
+bool
+ReflowInput::IsFloating() const
+{
+  return mStyleDisplay->IsFloating(mFrame);
+}
+
+mozilla::StyleDisplay
+ReflowInput::GetDisplay() const
+{
+  return mStyleDisplay->GetDisplay(mFrame);
+}