use bytesize, not length

lib/liquid/block_body.rb

@@ -115,7 +115,7 @@ module Liquid
     end
 
     def check_resources(context, node_output)
-      context.resource_limits.render_length += node_output.length
+      context.resource_limits.render_length += node_output.bytesize
       return unless context.resource_limits.reached?
       raise MemoryError.new("Memory limits exceeded".freeze)
     end

lib/liquid/tags/assign.rb

@@ -37,7 +37,7 @@ module Liquid
 
     def assign_score_of(val)
       if val.instance_of?(String)
-        val.length
+        val.bytesize
       elsif val.instance_of?(Array) || val.instance_of?(Hash)
         sum = 1
         # Uses #each to avoid extra allocations.

lib/liquid/tags/capture.rb

@@ -25,7 +25,7 @@ module Liquid
     def render(context)
       output = super
       context.scopes.last[@to] = output
-      context.resource_limits.assign_score += output.length
+      context.resource_limits.assign_score += output.bytesize
       ''.freeze
     end