fix(item-sliding): options display on rtl (#27203)

Issue URL: resolves #26103, resolves #25285

---------

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## What is the current behavior?
<!-- Please describe the current behavior that you are modifying. -->

Options in `item-sliding` will not display when using RTL with Firefox
and Safari.

<!-- Issues are required for both bug fixes and features. -->


## What is the new behavior?
<!-- Please describe the behavior or changes that are being added by
this PR. -->

Issue was coming from `:host-context`. Firefox would keep [removing the
entire](https://www.w3.org/TR/selectors-3/#grouping) compiled style when
using this unsupported style. This would led to the RTL styles to not
being applied to the component.

- Split the CSS group from `add-root-selector()`
- Added comments to make it easier to navigate through
`add-root-selector()`
- Added `:dir()`

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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and migration path for existing applications below. -->


## Other information

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screenshots of how the component looks before and after the change. -->

Co-authored-by: brandyscarney <brandyscarney@users.noreply.github.com>

- Updating `add-root-selector()` would also fix another
[issue](https://github.com/ionic-team/ionic-framework/issues/25285)
unintentionally

---------

Co-authored-by: ionitron <hi@ionicframework.com>
Co-authored-by: Liam DeBeasi <liamdebeasi@users.noreply.github.com>

core/src/themes/ionic.functions.string.scss

@@ -84,23 +84,7 @@
 
 // Add Root Selector
 // --------------------------------------------------------------------------------
-// Adds a root selector using host-context based on the selector passed
+// Adds a root selector using host based on the selector passed
-//
-// Examples
-// --------------------------------------------------------------------------------
-// @include add-root-selector("[dir=rtl]", ":host")
-// --> :host-context([dir=rtl])
-//
-// @include add-root-selector("[dir=rtl]", ":host(.fixed)")
-// --> :host-context([dir=rtl]):host(.fixed)
-// --> :host-context([dir=rtl]).fixed
-//
-// @include add-root-selector("[dir=rtl]", ":host(.tab-layout-icon-hide) ::slotted(ion-badge)")
-// --> :host-context([dir=rtl]).tab-layout-icon-hide ::slotted(ion-badge)
-//
-// @include add-root-selector("[dir=rtl]", ".shadow")
-// --> [dir=rtl] .shadow
-// --> :host-context([dir=rtl]) .shadow
 // --------------------------------------------------------------------------------
 
 @function add-root-selector($root, $addHostSelector) {
@@ -110,8 +94,13 @@
 
   @each $selector in $selectors {
     // If the selector contains :host( it means it is targeting a class on the host
-    // element so we need to change how we target it
+    // element so we need to change how we target it:
+    // @include add-root-selector(":host(.fixed)", "[dir=rtl]")
+    // --> :host-context([dir=rtl]):host(.fixed)
+    // --> :host-context([dir=rtl]).fixed
     @if str-contains($selector, ":host(") {
+      // @include add-root-selector(":host(.fixed)", "[dir=rtl]")
+      // --> :host-context([dir=rtl]):host(.fixed)
       $shadow-element: str-replace($selector, ":host(", ":host-context(#{$addHostSelector}):host(");
       $list: append($list, $shadow-element, comma);
 
@@ -122,26 +111,63 @@
         @if str-contains($element, ":host(") {
           $scoped-element: $element;
 
-          @if str-contains($element, "))") {
+          // Replace the :host( and ) so all we have left is the class
-            $scoped-element: str-replace($scoped-element, "))", ")");
+          // inside of it:
-          } @else {
+          // :host(.fixed) -> .fixed
           $scoped-element: str-replace($scoped-element, ")", "");
-          }
+          $scoped-element: str-replace($scoped-element, ":host(", "");
-          $scoped-element: str-replace($scoped-element, ":host(", ":host-context(#{$addHostSelector})");
 
+          // Add the class back inside of host with the rtl selector:
+          // .fixed -> :host-context([dir=rtl]).fixed
+          $scoped-element: str-replace($scoped-element, $scoped-element, ":host-context(#{$addHostSelector})#{$scoped-element}");
+
+          // @include add-root-selector(":host(.fixed)", "[dir=rtl]")
+          // --> :host-context([dir=rtl]).fixed
           $new-element: append($new-element, $scoped-element, space);
         } @else {
+          // Add back any selectors that followed the host after transforming the
+          // first selector:
+          // :host(.fixed) ::slotted(ion-icon)
+          // --> :host-context([dir=rtl]):host(.fixed) ::slotted(ion-icon)
+          // --> :host-context([dir=rtl]).fixed ::slotted(ion-icon)
           $new-element: append($new-element, $element, space);
         }
       }
 
       $list: append($list, $new-element, comma);
-    // If the selector contains :host it means it is targeting just the host
+    // If the selector contains :host without a parantheses
+    // it means it is targeting just the host
     // element so we can change it to look for host-context
+    // @include add-root-selector(":host", "[dir=rtl]")
+    // --> :host-context([dir=rtl])
+    // --> :host:dir(rtl)
     } @else if str-contains($selector, ":host") {
-      $list: append($list, ":host-context(#{$addHostSelector})", comma);
+      $new-element: ();
+      $elements: str-split($selector, " ");
+
+      @each $element in $elements {
+        @if str-contains($element, ":host") {
+          // Replace the :host with the addHostSelector:
+          // :host -> :host-context([dir=rtl])
+          $updated-element: str-replace($element, ":host", ":host-context(#{$addHostSelector})");
+
+          // Add the final selector after all transformations:
+          // :host -> :host-context([dir=rtl])
+          $new-element: append($new-element, $updated-element, space);
+        } @else {
+          // Add back any selectors that followed the host after transforming the
+          // first selector:
+          // :host ::slotted(ion-icon) -> :host-context([dir=rtl]) ::slotted(ion-icon)
+          $new-element: append($new-element, $element, space);
+        }
+      }
+      
+      $list: append($list, $new-element, comma);
     // If the selector does not contain host at all it is either a shadow
-    // or normal element so append both the dir check and host-context
+    // or normal element so append both the addHostSelector and host-context
+    // @include add-root-selector("ion-component", "[dir=rtl]")
+    // --> :host-context([dir=rtl]) ion-component
+    // --> [dir=rtl] ion-component
     } @else {
       $list: append($list, "#{$addHostSelector} #{$selector}", comma);
       $list: append($list, ":host-context(#{$addHostSelector}) #{$selector}", comma);

core/src/themes/ionic.mixins.scss

@@ -194,11 +194,69 @@
 @mixin rtl() {
   $root: #{&};
 
-  @at-root #{add-root-selector($root, "[dir=rtl]")} {
+  $rootSplit: str-split($root, ",");
+  $selectors: #{add-root-selector($root, "[dir=rtl]")};
+  $selectorsSplit: str-split($selectors, ",");
+
+  $hostContextSelectors: ();
+  $restSelectors: ();
+  $dirSelectors: ();
+
+  // Selectors must be split into individual selectors in case the browser
+  // doesn't support a specific selector.
+  // For example, Firefox and Safari doesn't support `:host-context()`.
+  // If an invalid selector is used, then the entire group of selectors
+  // will be ignored.
+  // @link https://www.w3.org/TR/selectors-3/#grouping
+  @each $selector in $selectorsSplit {
+    // Group the selectors back into a single selector to optimize the output.
+    @if str-index($selector, ":host-context") {
+      $hostContextSelectors: append($hostContextSelectors, $selector, comma);
+    } @else {
+      // Group the selectors back into a single selector to optimize the output.
+      $restSelectors: append($restSelectors, $selector, comma);
+    }
+  }
+  
+  // Supported by Chrome.
+  @if length($hostContextSelectors) > 0 {
+    @at-root #{$hostContextSelectors} {
       @content;
     }
   }
 
+  // Supported by all browsers.
+  @if length($restSelectors) > 0 {
+    @at-root #{$restSelectors} {
+      @content;
+    }
+  }
+
+  // If browser can support `:dir()`, then add the `:dir()` selectors.
+  @supports selector(:dir(rtl)) {
+    // Adding :dir() in case the browser doesn't support `:host-context()` and does support `:dir()`.
+    // `:host-context()` is added:
+    // - through the `add-root-selector()` function.
+    // - first so that it takes precedence over `:dir()`.
+    // For example,
+    // - Firefox doesn't support `:host-context()`, but does support `:dir()`.
+    // - Safari doesn't support `:host-context()`, but Safari 16.4+ supports `:dir()`
+    // @link https://webkit.org/blog/13966/webkit-features-in-safari-16-4/
+    @each $selector in $rootSplit {
+      $dirSelector: "#{$selector}:dir(rtl)";
+      // Group the selectors back into a single selector to optimize the output.
+      $dirSelectors: append($dirSelectors, $dirSelector, comma);
+    }
+
+    // Supported by Firefox.
+    @if length($dirSelectors) > 0 {
+      @at-root #{$dirSelectors} {
+        @content;
+      }
+    }
+  }
+}
+
 @mixin ltr() {
   @content;
 }