Make the stack_trace package print relative URLs for browser paths.

pkg/stack_trace/lib/src/frame.dart

Index: pkg/stack_trace/lib/src/frame.dart
diff --git a/pkg/stack_trace/lib/src/frame.dart b/pkg/stack_trace/lib/src/frame.dart
index 6a88a268c93a6d09d8064c81090dd9713ace6b7b..74aafcda319f767b59f0ad4dec4552d965115a54 100644
--- a/pkg/stack_trace/lib/src/frame.dart
+++ b/pkg/stack_trace/lib/src/frame.dart
@@ -69,7 +69,8 @@ class Frame {
   /// This will usually be the string form of [uri], but a relative URI will be
   /// used if possible.
   String get library {
-    if (uri.scheme != 'file') return uri.toString();
+    if (uri.scheme != Uri.base.scheme) return uri.toString();
+    if (path.style == path.Style.url) return path.relative(uri.toString());
     return path.relative(path.fromUri(uri));
   }