Add a complex reload test that rebases the root script path three times.

runtime/observatory/lib/src/service/object.dart

Index: runtime/observatory/lib/src/service/object.dart
diff --git a/runtime/observatory/lib/src/service/object.dart b/runtime/observatory/lib/src/service/object.dart
index e0f6e055920eee8fa6b9a594f19a7a0e95bfa2ca..662cd87e1bb72d15051176331f7406ec55393212 100644
--- a/runtime/observatory/lib/src/service/object.dart
+++ b/runtime/observatory/lib/src/service/object.dart
@@ -1333,9 +1333,14 @@ class Isolate extends ServiceObjectOwner implements M.Isolate {
     return invokeRpc('getSourceReport', params);
   }
 
-  Future<ServiceMap> reloadSources() {
-    return invokeRpc('_reloadSources', {}).then((_) {
+  Future<ServiceMap> reloadSources(
+      [Map<String, dynamic> params]) {

[turnidge, 2016/11/18 19:23:10]

I would prefer a named optional parameter for "rootLibUri".

[Cutch, 2016/11/18 20:23:19]

Done.

+    if (params == null) {
+      params = <String, dynamic>{};
+    }
+    return invokeRpc('reloadSources', params).then((result) {
       reloading = true;
+      return result;
     });
   }