Fix runtime cast issue

pkgs/glob/lib/src/ast.dart

diff --git a/pkgs/glob/lib/src/ast.dart b/pkgs/glob/lib/src/ast.dart
index 130342e..809d4bc 100644
--- a/pkgs/glob/lib/src/ast.dart
+++ b/pkgs/glob/lib/src/ast.dart
@@ -147,7 +147,7 @@
 
       var text = literal.text;
       if (context.style == p.Style.windows) text = text.replaceAll("/", "\\");
-      var components = context.split(text);
+      Iterable<String> components = context.split(text);
 
       // If the first component is absolute, that means it's a separator (on
       // Windows some non-separator things are also absolute, but it's invalid