linter: Simplify lintPubspecSource

A `results` variable was declared in this function, and then just
always returned as empty. Since it only ever returned an empty list,
we refactor it to just return `void`.

Change-Id: Ic785365e3b79666a8a46a595bc656e9b3f1c42e0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/394384
Auto-Submit: Samuel Rawlins <[email protected]>
Reviewed-by: Phil Quitslund <[email protected]>
Commit-Queue: Phil Quitslund <[email protected]>

pkg/linter/lib/src/test_utilities/test_linter.dart

@@ -44,20 +44,17 @@ class TestLinter implements AnalysisErrorListener {
     var errors = <AnalysisErrorInfo>[];
     var lintDriver = LintDriver(options, _resourceProvider);
     errors.addAll(await lintDriver.analyze(files.where(isDartFile)));
-    files.where(isPubspecFile).forEach((file) {
-      var errorsForFile = lintPubspecSource(
+    for (var file in files.where(isPubspecFile)) {
+      lintPubspecSource(
         contents: file.readAsStringSync(),
         sourcePath: _resourceProvider.pathContext.normalize(file.absolute.path),
       );
-      errors.addAll(errorsForFile);
-    });
+    }
     return errors;
   }
 
   @visibleForTesting
-  Iterable<AnalysisErrorInfo> lintPubspecSource(
-      {required String contents, String? sourcePath}) {
-    var results = <AnalysisErrorInfo>[];
+  void lintPubspecSource({required String contents, String? sourcePath}) {
     var sourceUrl = sourcePath == null ? null : path.toUri(sourcePath);
     var spec = Pubspec.parse(contents, sourceUrl: sourceUrl);
 
@@ -78,8 +75,6 @@ class TestLinter implements AnalysisErrorListener {
         }
       }
     }
-
-    return results;
   }
 
   @override