Address PR feedback.

Revert parser changes.  Instead look at node span line numbers to determine whether a loud comment is trailing.

Add some more test cases.

lib/src/ast/css/comment.dart

@@ -16,9 +16,5 @@ abstract class CssComment extends CssNode {
   /// compressed mode.
   bool get isPreserved;
 
-  /// Whether this comment follows non-comment text on a line and should remain
-  /// attached to that non-comment text when being serialized.
-  bool get isTrailing;
-
   T accept<T>(CssVisitor<T> visitor) => visitor.visitCssComment(this);
 }

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

@@ -13,12 +13,10 @@ import 'node.dart';
 class ModifiableCssComment extends ModifiableCssNode implements CssComment {
   final String text;
   final FileSpan span;
-  final bool _isTrailing;
 
   bool get isPreserved => text.codeUnitAt(2) == $exclamation;
-  bool get isTrailing => _isTrailing;
 
-  ModifiableCssComment(this.text, this.span, this._isTrailing);
+  ModifiableCssComment(this.text, this.span);
 
   T accept<T>(ModifiableCssVisitor<T> visitor) => visitor.visitCssComment(this);
 }

lib/src/ast/sass/statement/loud_comment.dart

@@ -15,11 +15,7 @@ class LoudComment implements Statement {
 
   FileSpan get span => text.span;
 
-  /// Whether this comment follows non-comment text on a line and should remain
-  /// attached to that non-comment text when being serialized.
-  final bool isTrailing;
-
-  LoudComment(this.text, this.isTrailing);
+  LoudComment(this.text);
 
   T accept<T>(StatementVisitor<T> visitor) => visitor.visitLoudComment(this);
 

lib/src/parse/sass.dart

@@ -9,7 +9,6 @@ import '../ast/sass.dart';
 import '../interpolation_buffer.dart';
 import '../logger.dart';
 import '../util/character.dart';
-import '../value.dart';
 import 'stylesheet.dart';
 
 /// A parser for the indented syntax.
@@ -99,21 +98,9 @@ class SassParser extends StylesheetParser {
       scanner.readChar();
       next = scanner.peekChar();
     }
-    var url = scanner.substring(start.position);
-    var span = scanner.spanFrom(start);
-
-    if (isPlainImportUrl(url)) {
-      // Serialize [url] as a Sass string because [StaticImport] expects it to
-      // include quotes.
-      return StaticImport(
-          Interpolation([SassString(url).toString()], span), span);
-    } else {
-      try {
-        return DynamicImport(parseImportUrl(url), span);
-      } on FormatException catch (innerError) {
-        error("Invalid URL: ${innerError.message}", span);
-      }
-    }
+
+    return DynamicImport(parseImportUrl(scanner.substring(start.position)),
+        scanner.spanFrom(start));
   }
 
   bool scanElse(int ifIndentation) {
@@ -306,8 +293,7 @@ class SassParser extends StylesheetParser {
     }
     if (!buffer.trailingString.trimRight().endsWith("*/")) buffer.write(" */");
 
-    // The sass syntax does not support trailing loud comments ==> isTrailing = false.
-    return LoudComment(buffer.interpolation(scanner.spanFrom(start)), false);
+    return LoudComment(buffer.interpolation(scanner.spanFrom(start)));
   }
 
   void whitespace() {

lib/src/parse/scss.dart

@@ -61,8 +61,8 @@ class ScssParser extends StylesheetParser {
 
   List<Statement> children(Statement child()) {
     scanner.expectChar($lbrace);
+    whitespaceWithoutComments();
     var children = <Statement>[];
-    _whitespaceAndOptionalTrailingLoudComment(children);
     while (true) {
       switch (scanner.peekChar()) {
         case $dollar:
@@ -76,7 +76,7 @@ class ScssParser extends StylesheetParser {
               whitespaceWithoutComments();
               break;
             case $asterisk:
-              children.add(_loudComment(/* isTrailing= */ false));
+              children.add(_loudComment());
               whitespaceWithoutComments();
               break;
             default:
@@ -87,7 +87,7 @@ class ScssParser extends StylesheetParser {
 
         case $semicolon:
           scanner.readChar();
-          _whitespaceAndOptionalTrailingLoudComment(children);
+          whitespaceWithoutComments();
           break;
 
         case $rbrace:
@@ -103,7 +103,7 @@ class ScssParser extends StylesheetParser {
 
   List<Statement> statements(Statement statement()) {
     var statements = <Statement>[];
-    _whitespaceAndOptionalTrailingLoudComment(statements);
+    whitespaceWithoutComments();
     while (!scanner.isDone) {
       switch (scanner.peekChar()) {
         case $dollar:
@@ -117,7 +117,7 @@ class ScssParser extends StylesheetParser {
               whitespaceWithoutComments();
               break;
             case $asterisk:
-              statements.add(_loudComment(/* isTrailing= */ false));
+              statements.add(_loudComment());
               whitespaceWithoutComments();
               break;
             default:
@@ -129,7 +129,7 @@ class ScssParser extends StylesheetParser {
 
         case $semicolon:
           scanner.readChar();
-          _whitespaceAndOptionalTrailingLoudComment(statements);
+          whitespaceWithoutComments();
           break;
 
         default:
@@ -163,7 +163,7 @@ class ScssParser extends StylesheetParser {
   }
 
   /// Consumes a statement-level loud comment block.
-  LoudComment _loudComment(bool isTrailing) {
+  LoudComment _loudComment() {
     var start = scanner.state;
     scanner.expect("/*");
     var buffer = InterpolationBuffer()..write("/*");
@@ -182,8 +182,7 @@ class ScssParser extends StylesheetParser {
           if (scanner.peekChar() != $slash) break;
 
           buffer.writeCharCode(scanner.readChar());
-          return LoudComment(
-              buffer.interpolation(scanner.spanFrom(start)), isTrailing);
+          return LoudComment(buffer.interpolation(scanner.spanFrom(start)));
 
         case $cr:
           scanner.readChar();
@@ -201,26 +200,4 @@ class ScssParser extends StylesheetParser {
       }
     }
   }
-
-  /// Consumes whitespace and optionally a trailing loud comment, adding the
-  /// trailing loud comment to [statements] if consumed.
-  ///
-  /// A trailing loud comment is only possible if the initially consumed
-  /// whitespace lacks any newlines.  If that's the case and a loud comment
-  /// immediately follows, the loud comment will also be consumed.
-  void _whitespaceAndOptionalTrailingLoudComment(List<Statement> statements) {
-    bool sawAnyNewlines = whitespaceWithoutComments();
-    if (_peekForStartOfLoudComment()) {
-      bool isTrailing = !sawAnyNewlines;
-      statements.add(_loudComment(isTrailing));
-      whitespaceWithoutComments();
-    }
-  }
-
-  /// Returns whether the scanner is pointing at the start of a loud comment.
-  bool _peekForStartOfLoudComment() {
-    return !scanner.isDone &&
-        scanner.peekChar() == $slash &&
-        scanner.peekChar(1) == $asterisk;
-  }
 }

lib/src/visitor/async_evaluate.dart

@@ -1500,7 +1500,7 @@ class _EvaluateVisitor
     }
 
     _parent.addChild(ModifiableCssComment(
-        await _performInterpolation(node.text), node.span, node.isTrailing));
+        await _performInterpolation(node.text), node.span));
     return null;
   }
 
@@ -2424,8 +2424,7 @@ class _EvaluateVisitor
       _endOfImports++;
     }
 
-    _parent
-        .addChild(ModifiableCssComment(node.text, node.span, node.isTrailing));
+    _parent.addChild(ModifiableCssComment(node.text, node.span));
   }
 
   Future<void> visitCssDeclaration(CssDeclaration node) async {

lib/src/visitor/clone_css.dart

@@ -37,7 +37,7 @@ class _CloneCssVisitor implements CssVisitor<ModifiableCssNode> {
   }
 
   ModifiableCssComment visitCssComment(CssComment node) =>
-      ModifiableCssComment(node.text, node.span, node.isTrailing);
+      ModifiableCssComment(node.text, node.span);
 
   ModifiableCssDeclaration visitCssDeclaration(CssDeclaration node) =>
       ModifiableCssDeclaration(node.name, node.value, node.span,

lib/src/visitor/evaluate.dart

@@ -5,7 +5,7 @@
 // DO NOT EDIT. This file was generated from async_evaluate.dart.
 // See tool/grind/synchronize.dart for details.
 //
-// Checksum: 56067ad7a31ee7adf5bb4e9d484fe95f38d3762c
+// Checksum: f4f4c5d1cbc9894d14b6d8ce7c1a3c09146db9ba
 //
 // ignore_for_file: unused_import
 
@@ -1498,8 +1498,8 @@ class _EvaluateVisitor
       _endOfImports++;
     }
 
-    _parent.addChild(ModifiableCssComment(
-        _performInterpolation(node.text), node.span, node.isTrailing));
+    _parent.addChild(
+        ModifiableCssComment(_performInterpolation(node.text), node.span));
     return null;
   }
 
@@ -2409,8 +2409,7 @@ class _EvaluateVisitor
       _endOfImports++;
     }
 
-    _parent
-        .addChild(ModifiableCssComment(node.text, node.span, node.isTrailing));
+    _parent.addChild(ModifiableCssComment(node.text, node.span));
   }
 
   void visitCssDeclaration(CssDeclaration node) {