Just to be sure, made it more explicitly root files

Josh Goldberg · web-flow · commit c53d106ae167 · 2018-02-14T10:01:31.000-08:00
diff --git a/.istanbul.yml b/.istanbul.yml
@@ -1,5 +1,5 @@
 instrumentation:
   excludes:
-    - "*"
     - "**/*.runtime.js"
+    - "./*"
     - ".github/*"
