Add a benchmark for capture vs. assign in Liquid. [ci skip]

benchmark/capture-assign.rb

@@ -0,0 +1,20 @@
+require "liquid"
+require "benchmark/ips"
+
+puts "Ruby #{RUBY_VERSION}-p#{RUBY_PATCHLEVEL}"
+puts "Liquid #{Liquid::VERSION}"
+
+template1 = '{% capture foobar %}foo{{ bar }}{% endcapture %}{{ foo }}{{ foobar }}'
+template2 = '{% assign foobar = "foo" | append: bar %}{{ foobar }}'
+
+def render(template)
+    Liquid::Template.parse(template).render("bar" => "42")
+end
+
+puts render(template1)
+puts render(template2)
+
+Benchmark.ips do |x|
+  x.report('capture') { render(template1) }
+  x.report('assign')  { render(template2) }
+end