Allow more user action pseudo classes after -webkit-scrollbar

Fixes parcel-bundler/parcel#7885

Author: devongovett

selectors/parser.rs

@@ -55,7 +55,11 @@ pub trait NonTSPseudoClass<'i>: Sized + ToCss {
   /// https://drafts.csswg.org/selectors-4/#useraction-pseudos
   fn is_user_action_state(&self) -> bool;
 
-  fn is_webkit_scrollbar_state(&self) -> bool {
+  fn is_valid_before_webkit_scrollbar(&self) -> bool {
+    false
+  }
+
+  fn is_valid_after_webkit_scrollbar(&self) -> bool {
     false
   }
 
@@ -2591,14 +2595,14 @@ where
 
   let pseudo_class = P::parse_non_ts_pseudo_class(parser, location, name)?;
   if state.intersects(SelectorParsingState::AFTER_WEBKIT_SCROLLBAR) {
-    if !pseudo_class.is_webkit_scrollbar_state() {
+    if !pseudo_class.is_valid_after_webkit_scrollbar() {
       return Err(location.new_custom_error(SelectorParseErrorKind::InvalidPseudoClassAfterWebKitScrollbar));
     }
   } else if state.intersects(SelectorParsingState::AFTER_PSEUDO_ELEMENT) {
     if !pseudo_class.is_user_action_state() {
       return Err(location.new_custom_error(SelectorParseErrorKind::InvalidPseudoClassAfterPseudoElement));
     }
-  } else if pseudo_class.is_webkit_scrollbar_state() {
+  } else if !pseudo_class.is_valid_before_webkit_scrollbar() {
     return Err(location.new_custom_error(SelectorParseErrorKind::InvalidPseudoClassBeforeWebKitScrollbar));
   }
   Ok(Component::NonTSPseudoClass(pseudo_class))

src/lib.rs

@@ -4565,6 +4565,10 @@ mod tests {
       "-webkit-resizer",
     ] {
       for class in [
+        "enabled",
+        "disabled",
+        "hover",
+        "active",
         "horizontal",
         "vertical",
         "decrement",
@@ -4611,7 +4615,7 @@ mod tests {
       "-webkit-resizer",
     ] {
       error_test(
-        &format!("::{}:hover {{color:red}}", element),
+        &format!("::{}:focus {{color:red}}", element),
         ParserError::SelectorError(SelectorError::InvalidPseudoClassAfterWebKitScrollbar),
       );
     }

src/selector.rs

@@ -403,11 +403,30 @@ impl<'i> parcel_selectors::parser::NonTSPseudoClass<'i> for PseudoClass<'i> {
   }
 
   fn is_user_action_state(&self) -> bool {
-    matches!(*self, PseudoClass::Active | PseudoClass::Hover | PseudoClass::Focus)
+    matches!(
+      *self,
+      PseudoClass::Active
+        | PseudoClass::Hover
+        | PseudoClass::Focus
+        | PseudoClass::FocusWithin
+        | PseudoClass::FocusVisible
+    )
+  }
+
+  fn is_valid_before_webkit_scrollbar(&self) -> bool {
+    !matches!(*self, PseudoClass::WebKitScrollbar(..))
   }
 
-  fn is_webkit_scrollbar_state(&self) -> bool {
-    matches!(*self, PseudoClass::WebKitScrollbar(..))
+  fn is_valid_after_webkit_scrollbar(&self) -> bool {
+    // https://github.com/WebKit/WebKit/blob/02fbf9b7aa435edb96cbf563a8d4dcf1aa73b4b3/Source/WebCore/css/parser/CSSSelectorParser.cpp#L285
+    matches!(
+      *self,
+      PseudoClass::WebKitScrollbar(..)
+        | PseudoClass::Enabled
+        | PseudoClass::Disabled
+        | PseudoClass::Hover
+        | PseudoClass::Active
+    )
   }
 }