[FlexNG] Accommodate RTL flex containers

FlexibleBoxAlgorithm flips the positions of items in RTL row containers.
Legacy flips items in RTL column containers before setting their
positions and I thought I'd have to do something similar in LayoutNG.

But LayoutNG assumes children will be positioned without flipping for
RTL; the fragment flips children automatically upon creation [1]. So
this patch prevents FlexibleBoxAlgorithm from flipping for RTL in
FlexNG.

[1] https://cs.chromium.org/chromium/src/third_party/blink/renderer/core/layout/ng/ng_physical_container_fragment.cc?rcl=70b1c5fbc63772bd98d26d26ddded71ca96f5f1f&l=76

Bug: 845235
Change-Id: I672b0b8b4f9781c54edaa60cb2ce7e0f46610cec
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1889011Reviewed-by: Christian Biesinger <cbiesinger@chromium.org>
Commit-Queue: David Grogan <dgrogan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713165}

third_party/blink/renderer/core/layout/flexible_box_algorithm.cc

@@ -487,9 +487,15 @@ void FlexLine::ComputeLineItemsPosition(LayoutUnit main_axis_offset,
   sum_justify_adjustments += initial_position;
   LayoutUnit max_descent;  // Used when align-items: baseline.
   LayoutUnit max_child_cross_axis_extent;
-  bool should_flip_main_axis =
-      !algorithm->StyleRef().ResolvedIsColumnFlexDirection() &&
-      !algorithm->IsLeftToRightFlow();
+  bool should_flip_main_axis;
+  if (algorithm->IsNGFlexBox()) {
+    should_flip_main_axis =
+        algorithm->StyleRef().ResolvedIsRowReverseFlexDirection();
+  } else {
+    should_flip_main_axis =
+        !algorithm->StyleRef().ResolvedIsColumnFlexDirection() &&
+        !algorithm->IsLeftToRightFlow();
+  }
   LayoutUnit width_for_rtl = container_logical_width;
   // -webkit-box always started layout at an origin of 0, regardless of
   // direction.
@@ -960,6 +966,9 @@ void FlexLayoutAlgorithm::LayoutColumnReverse(
       // We passed 0 as the initial main_axis offset to ComputeLineItemsPosition
       // for ColumnReverse containers so here we have to add the
       // border_scrollbar_padding of the container.
+      // TODO(dgrogan): I think
+      // wpt/css/css-flexbox/flex-lines/multi-line-wrap-with-column-reverse.html
+      // fails because this totally ignores margins.
       flex_item.desired_location.SetX(
           main_axis_content_size + border_scrollbar_padding_before -
           flex_item.desired_location.X() - item_main_size);
@@ -967,4 +976,12 @@ void FlexLayoutAlgorithm::LayoutColumnReverse(
   }
 }
 
+bool FlexLayoutAlgorithm::IsNGFlexBox() const {
+  DCHECK(!all_items_.IsEmpty())
+      << "You can't call IsNGFlexBox before adding items.";
+  // The FlexItems created by legacy will have an empty ng_input_node. An NG
+  // FlexItem's ng_input_node will have a LayoutBox.
+  return all_items_.at(0).ng_input_node.GetLayoutBox();
+}
+
 }  // namespace blink

third_party/blink/renderer/core/layout/flexible_box_algorithm.h

@@ -417,6 +417,7 @@ class FlexLayoutAlgorithm {
 
   void LayoutColumnReverse(LayoutUnit main_axis_content_size,
                            LayoutUnit border_scrollbar_padding_before);
+  bool IsNGFlexBox() const;
 
  private:
   EOverflow MainAxisOverflowForChild(const LayoutBox& child) const;

third_party/blink/renderer/core/layout/ng/ng_flex_layout_algorithm.cc

@@ -665,9 +665,6 @@ void NGFlexLayoutAlgorithm::GiveLinesAndItemsFinalPositionAndSize() {
       if (DoesItemStretch(flex_item.ng_input_node))
         ApplyStretchAlignmentToChild(flex_item);
 
-      // TODO(dgrogan): Implement behavior from legacy's
-      // FlipForRightToLeftColumn here.
-
       // flex_item.desired_location stores the main axis offset in X and the
       // cross axis offset in Y. But AddChild wants offset from parent
       // rectangle, so we have to transpose for columns. AddChild takes care of

third_party/blink/web_tests/TestExpectations

@@ -1383,16 +1383,12 @@ crbug.com/591099 external/wpt/css/css-flexbox/flexbox_align-items-stretch-3.html
 
 ### virtual/layout_ng_flex_box/css3/flexbox/
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/auto-height-column-with-border-and-padding.html [ Failure ]
-crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-align-end.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-align-vertical-writing-mode.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-align.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-flow-2.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-flow-auto-margins.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-flow-border.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-flow-margins-auto-size.html [ Failure ]
-crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-flow-margins.html [ Failure ]
-crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-flow-orientations.html [ Failure ]
-crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-flow-overflow.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-flow-padding.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-flow.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-order.html [ Failure ]
@@ -1400,10 +1396,7 @@ crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flexbox-baseline-margin
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flexbox-baseline.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flexbox-overflow-auto.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/minimum-size-image.html [ Failure ]
-crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/multiline-align-self.html [ Failure ]
-crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/multiline-justify-content.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/multiline-reverse-wrap-baseline.html [ Failure ]
-crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/multiline.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/negative-overflow.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/order-painting.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/overflow-auto-resizes-correctly.html [ Failure ]
@@ -1411,8 +1404,6 @@ crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/percentage-height-repla
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/position-absolute-child.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/relpos-with-percentage-top.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/style-change.html [ Failure ]
-crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/true-centering.html [ Failure ]
-crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/writing-modes.html [ Failure ]
 
 ### virtual/layout_ng_flex_box/css3/flexbox/mozilla/
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/mozilla/flexbox-items-as-stacking-contexts-2.html [ Failure ]
@@ -1425,7 +1416,6 @@ crbug.com/591099 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/anonymo
 crbug.com/591099 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/anonymous-flex-item-003.html [ Failure ]
 crbug.com/807497 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/anonymous-flex-item-005.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/flex-basis-010.html [ Failure ]
-crbug.com/591099 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/flex-direction-row-vertical.html [ Failure ]
 crbug.com/249112 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/flex-minimum-height-flex-items-005.xht [ Failure ]
 crbug.com/249112 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/flex-minimum-height-flex-items-007.xht [ Failure ]
 crbug.com/996474 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/flex-minimum-height-flex-items-009.html [ Pass Failure ]