Add frozen test to static registers

.rubocop.yml

@@ -1,5 +1,5 @@
 inherit_from:
-  - 'https://shopify.github.io/ruby-style-guide/rubocop.yml'
+  - https://shopify.github.io/ruby-style-guide/rubocop.yml
   - .rubocop_todo.yml
 
 require: rubocop-performance
@@ -10,7 +10,7 @@ Performance:
 AllCops:
   Exclude:
     - 'vendor/bundle/**/*'
-
+      
 Naming/MethodName:
   Exclude:
-    - 'example/server/liquid_servlet.rb'
+    - 'example/server/liquid_servlet.rb'

.travis.yml

@@ -7,6 +7,8 @@ rvm:
   - &latest_ruby 2.6
   - 2.7
   - ruby-head
+  - jruby-head
+  - truffleruby
 
 matrix:
   include:
@@ -15,6 +17,8 @@ matrix:
       name: Profiling Memory Usage
   allow_failures:
     - rvm: ruby-head
+    - rvm: jruby-head
+    - rvm: truffleruby
 
 branches:
   only: