Change new List(n) to return fixed length list.

pkg/pathos/lib/path.dart

Index: pkg/pathos/lib/path.dart
diff --git a/pkg/pathos/lib/path.dart b/pkg/pathos/lib/path.dart
index 639bab5e660390091e887f9d93dec91f62413128..2b6fe471ee181dec6a5d49b34ba4306e3c737ffe 100644
--- a/pkg/pathos/lib/path.dart
+++ b/pkg/pathos/lib/path.dart
@@ -406,7 +406,8 @@ class Builder {
   List<String> split(String path) {
     var parsed = _parse(path);
     // Filter out empty parts that exist due to multiple separators in a row.
-    parsed.parts = parsed.parts.where((part) => !part.isEmpty).toList();
+    parsed.parts = parsed.parts.where((part) => !part.isEmpty)
+                               .toList(growable: true);
     if (parsed.root != null) parsed.parts.insertRange(0, 1, parsed.root);
     return parsed.parts;
   }