Don't mutate virtual_path, remove decorate

`virtual_path` is calculated in the constructor when the Template object
is allocated.  We don't actually need to set it in the `decorate`
method.  That means we can remove the decorate method all together.

actionview/lib/action_view/template.rb

@@ -122,10 +122,8 @@ module ActionView
 
     extend Template::Handlers
 
-    attr_accessor :virtual_path
-
     attr_reader :source, :identifier, :handler, :original_encoding, :updated_at
-    attr_reader :variable, :format, :variant, :locals
+    attr_reader :variable, :format, :variant, :locals, :virtual_path
 
     def initialize(source, identifier, handler, format: nil, variant: nil, locals: nil, **details)
       unless format
@@ -158,6 +156,7 @@ module ActionView
       @compile_mutex     = Mutex.new
     end
 
+    deprecate def virtual_path=(_); end
     deprecate def locals=(_); end
     deprecate def formats=(_); end
     deprecate def formats; Array(format); end

actionview/lib/action_view/template/resolver.rb

@@ -187,18 +187,10 @@ module ActionView
 
       if key
         @cache.cache(key, name, prefix, partial, locals) do
-          decorate(yield, path_info, details, locals)
+          yield
         end
       else
-        decorate(yield, path_info, details, locals)
-      end
-    end
-
-    # Ensures all the resolver information is set in the template.
-    def decorate(templates, path_info, details, locals)
-      cached = nil
-      templates.each do |t|
-        t.virtual_path ||= (cached ||= build_path(*path_info))
+        yield
       end
     end
   end
@@ -432,9 +424,5 @@ module ActionView
     def self.instances
       [new(""), new("/")]
     end
-
-    def decorate(*)
-      super.each { |t| t.virtual_path = nil }
-    end
   end
 end