remove assertions on data-reactroot

see facebook/react#10971

Author: Judahmeek

test/react/server_rendering/bundle_renderer_test.rb

@@ -36,7 +36,6 @@ class BundleRendererTest < ActiveSupport::TestCase
       result = @renderer.render("Todo", { todo: "write tests" }, nil)
 
       assert_match(%r{<li.*write tests</li>}, result)
-      assert_match(/data-reactroot/, result)
     end
 
     test "#render accepts strings" do
@@ -49,7 +48,6 @@ class BundleRendererTest < ActiveSupport::TestCase
       result = @renderer.render("Todo", { todo: "write more tests" }, :static)
 
       assert_match(%r{<li>write more tests</li>}, result)
-      assert_no_match(/data-reactroot/, result)
     end
 
     test "#render replays console messages" do # rubocop:disable Minitest/MultipleAssertions

test/react/server_rendering/exec_js_renderer_test.rb

@@ -32,14 +32,12 @@ class ExecJSRendererTest < ActiveSupport::TestCase
     result = @renderer.render("Todo", { todo: "write tests" }.to_json, {})
 
     assert_match(%r{<li.*write tests</li>}, result)
-    assert_match(/data-reactroot/, result)
   end
 
   test "#render accepts render_function:" do
     result = @renderer.render("Todo", { todo: "write more tests" }.to_json, render_function: "renderToStaticMarkup")
 
     assert_match(%r{<li>write more tests</li>}, result)
-    assert_no_match(/data-reactroot/, result)
   end
 
   test "#before_render is called before #after_render" do