layout: Allow transforming inline replaced elements (#31833)

This requires passing through information about whether or not the
element in question is replaced when checking to see if it's
transformable and transitively all functions that make decisions about
containing blocks. A new FragmentFlag is added to help track this -- it
will be set on both the replaced items BoxFragment container as well as
the Fragment for the replaced item itself.

Fixes #31806.

components/layout_2020/style_ext.rs

@@ -20,6 +20,7 @@ use style::Zero;
 use webrender_api as wr;
 
 use crate::dom_traversal::Contents;
+use crate::fragment_tree::FragmentFlags;
 use crate::geom::{
     AuOrAuto, LengthOrAuto, LengthPercentageOrAuto, LogicalSides, LogicalVec2, PhysicalSides,
     PhysicalSize,
@@ -179,13 +180,19 @@ pub(crate) trait ComputedValuesExt {
         &self,
         containing_block_writing_mode: WritingMode,
     ) -> LogicalSides<LengthPercentageOrAuto<'_>>;
-    fn has_transform_or_perspective(&self) -> bool;
+    fn has_transform_or_perspective(&self, fragment_flags: FragmentFlags) -> bool;
     fn effective_z_index(&self) -> i32;
     fn establishes_block_formatting_context(&self) -> bool;
-    fn establishes_stacking_context(&self) -> bool;
+    fn establishes_stacking_context(&self, fragment_flags: FragmentFlags) -> bool;
     fn establishes_scroll_container(&self) -> bool;
-    fn establishes_containing_block_for_absolute_descendants(&self) -> bool;
-    fn establishes_containing_block_for_all_descendants(&self) -> bool;
+    fn establishes_containing_block_for_absolute_descendants(
+        &self,
+        fragment_flags: FragmentFlags,
+    ) -> bool;
+    fn establishes_containing_block_for_all_descendants(
+        &self,
+        fragment_flags: FragmentFlags,
+    ) -> bool;
     fn background_is_transparent(&self) -> bool;
     fn get_webrender_primitive_flags(&self) -> wr::PrimitiveFlags;
 }
@@ -411,7 +418,7 @@ impl ComputedValuesExt for ComputedValues {
 
     /// Returns true if this style has a transform, or perspective property set and
     /// it applies to this element.
-    fn has_transform_or_perspective(&self) -> bool {
+    fn has_transform_or_perspective(&self, fragment_flags: FragmentFlags) -> bool {
         // "A transformable element is an element in one of these categories:
         //   * all elements whose layout is governed by the CSS box model except for
         //     non-replaced inline boxes, table-column boxes, and table-column-group
@@ -420,8 +427,9 @@ impl ComputedValuesExt for ComputedValues {
         //     elements with the exception of any descendant element of text content
         //     elements."
         // https://drafts.csswg.org/css-transforms/#transformable-element
-        // FIXME(mrobinson): Properly handle tables and replaced elements here.
-        if self.get_box().display.is_inline_flow() {
+        if self.get_box().display.is_inline_flow() &&
+            !fragment_flags.contains(FragmentFlags::IS_REPLACED)
+        {
             return false;
         }
 
@@ -464,7 +472,7 @@ impl ComputedValuesExt for ComputedValues {
     }
 
     /// Returns true if this fragment establishes a new stacking context and false otherwise.
-    fn establishes_stacking_context(&self) -> bool {
+    fn establishes_stacking_context(&self, fragment_flags: FragmentFlags) -> bool {
         let effects = self.get_effects();
         if effects.opacity != 1.0 {
             return true;
@@ -474,7 +482,7 @@ impl ComputedValuesExt for ComputedValues {
             return true;
         }
 
-        if self.has_transform_or_perspective() {
+        if self.has_transform_or_perspective(fragment_flags) {
             return true;
         }
 
@@ -513,8 +521,11 @@ impl ComputedValuesExt for ComputedValues {
     /// descendants) this method will return true, but a true return value does
     /// not imply that the style establishes a containing block for all descendants.
     /// Use `establishes_containing_block_for_all_descendants()` instead.
-    fn establishes_containing_block_for_absolute_descendants(&self) -> bool {
-        if self.establishes_containing_block_for_all_descendants() {
+    fn establishes_containing_block_for_absolute_descendants(
+        &self,
+        fragment_flags: FragmentFlags,
+    ) -> bool {
+        if self.establishes_containing_block_for_all_descendants(fragment_flags) {
             return true;
         }
 
@@ -525,8 +536,11 @@ impl ComputedValuesExt for ComputedValues {
     /// all descendants, including fixed descendants (`position: fixed`).
     /// Note that this also implies that it establishes a containing block
     /// for absolute descendants (`position: absolute`).
-    fn establishes_containing_block_for_all_descendants(&self) -> bool {
-        if self.has_transform_or_perspective() {
+    fn establishes_containing_block_for_all_descendants(
+        &self,
+        fragment_flags: FragmentFlags,
+    ) -> bool {
+        if self.has_transform_or_perspective(fragment_flags) {
             return true;
         }