Avoid [this] in Dartdoc comments (#2273)

Dartdoc broke this in dart-lang/dartdoc#3765.

Author: nex3

lib/src/ast/css/modifiable/node.dart

@@ -17,7 +17,7 @@ abstract base class ModifiableCssNode extends CssNode {
   ModifiableCssParentNode? get parent => _parent;
   ModifiableCssParentNode? _parent;
 
-  /// The index of [this] in `parent.children`.
+  /// The index of `this` in `parent.children`.
   ///
   /// This makes [remove] more efficient.
   int? _indexInParent;
@@ -33,7 +33,7 @@ abstract base class ModifiableCssNode extends CssNode {
 
   T accept<T>(ModifiableCssVisitor<T> visitor);
 
-  /// Removes [this] from [parent]'s child list.
+  /// Removes `this` from [parent]'s child list.
   ///
   /// Throws a [StateError] if [parent] is `null`.
   void remove() {
@@ -65,10 +65,10 @@ abstract base class ModifiableCssParentNode extends ModifiableCssNode
       : _children = children,
         children = UnmodifiableListView(children);
 
-  /// Returns whether [this] is equal to [other], ignoring their child nodes.
+  /// Returns whether `this` is equal to [other], ignoring their child nodes.
   bool equalsIgnoringChildren(ModifiableCssNode other);
 
-  /// Returns a copy of [this] with an empty [children] list.
+  /// Returns a copy of `this` with an empty [children] list.
   ///
   /// This is *not* a deep copy. If other parts of this node are modifiable,
   /// they are shared between the new and old nodes.

lib/src/ast/sass/at_root_query.dart

@@ -61,7 +61,7 @@ final class AtRootQuery {
           {Object? url, Logger? logger, InterpolationMap? interpolationMap}) =>
       AtRootQueryParser(contents, url: url, logger: logger).parse();
 
-  /// Returns whether [this] excludes [node].
+  /// Returns whether `this` excludes [node].
   ///
   /// @nodoc
   @internal
@@ -76,6 +76,6 @@ final class AtRootQuery {
     };
   }
 
-  /// Returns whether [this] excludes an at-rule with the given [name].
+  /// Returns whether `this` excludes an at-rule with the given [name].
   bool excludesName(String name) => (_all || names.contains(name)) != include;
 }

lib/src/ast/sass/expression/binary_operation.dart

@@ -153,13 +153,13 @@ enum BinaryOperator {
   /// The modulo operator, `%`.
   modulo('modulo', '%', 6);
 
-  /// The English name of [this].
+  /// The English name of `this`.
   final String name;
 
-  /// The Sass syntax for [this].
+  /// The Sass syntax for `this`.
   final String operator;
 
-  /// The precedence of [this].
+  /// The precedence of `this`.
   ///
   /// An operator with higher precedence binds tighter.
   final int precedence;

lib/src/ast/sass/expression/list.dart

@@ -58,7 +58,7 @@ final class ListExpression implements Expression {
     return buffer.toString();
   }
 
-  /// Returns whether [expression], contained in [this], needs parentheses when
+  /// Returns whether [expression], contained in `this`, needs parentheses when
   /// printed as Sass source.
   bool _elementNeedsParens(Expression expression) => switch (expression) {
         ListExpression(

lib/src/ast/sass/expression/string.dart

@@ -23,7 +23,7 @@ final class StringExpression implements Expression {
   /// included.
   final Interpolation text;
 
-  /// Whether [this] has quotes.
+  /// Whether `this` has quotes.
   final bool hasQuotes;
 
   FileSpan get span => text.span;

lib/src/ast/sass/expression/unary_operation.dart

@@ -63,10 +63,10 @@ enum UnaryOperator {
   /// The boolean negation operator, `not`.
   not('not', 'not');
 
-  /// The English name of [this].
+  /// The English name of `this`.
   final String name;
 
-  /// The Sass syntax for [this].
+  /// The Sass syntax for `this`.
   final String operator;
 
   const UnaryOperator(this.name, this.operator);

lib/src/ast/selector.dart

@@ -83,7 +83,7 @@ abstract base class Selector implements AstNode {
 
   Selector(this.span);
 
-  /// Prints a warning if [this] is a bogus selector.
+  /// Prints a warning if `this` is a bogus selector.
   ///
   /// This may only be called from within a custom Sass function. This will
   /// throw a [SassException] in Dart Sass 2.0.0.

lib/src/ast/selector/list.dart

@@ -96,9 +96,9 @@ final class SelectorList extends Selector {
     return contents.isEmpty ? null : SelectorList(contents, span);
   }
 
-  /// Returns a new selector list that represents [this] nested within [parent].
+  /// Returns a new selector list that represents `this` nested within [parent].
   ///
-  /// By default, this replaces [ParentSelector]s in [this] with [parent]. If
+  /// By default, this replaces [ParentSelector]s in `this` with [parent]. If
   /// [preserveParentSelectors] is true, this instead preserves those selectors
   /// as parent selectors.
   ///

lib/src/ast/selector/pseudo.dart

@@ -174,7 +174,7 @@ final class PseudoSelector extends SimpleSelector {
     for (var simple in compound) {
       if (simple case PseudoSelector(isElement: true)) {
         // A given compound selector may only contain one pseudo element. If
-        // [compound] has a different one than [this], unification fails.
+        // [compound] has a different one than `this`, unification fails.
         if (isElement) return null;
 
         // Otherwise, this is a pseudo selector and should come before pseudo

lib/src/ast/selector/simple.dart

@@ -59,7 +59,7 @@ abstract base class SimpleSelector extends Selector {
               url: url, logger: logger, allowParent: allowParent)
           .parseSimpleSelector();
 
-  /// Returns a new [SimpleSelector] based on [this], as though it had been
+  /// Returns a new [SimpleSelector] based on `this`, as though it had been
   /// written with [suffix] at the end.
   ///
   /// Assumes [suffix] is a valid identifier suffix. If this wouldn't produce a