ERB::Util.html_escape stop trying to tidy bytes

This call to `Unicode.tidy_bytes` has been introduced 10 years
ago in rails#19992 but this pull
request has been merged by mistake and was supposed to be reverted.

Semantically it makes no sense to deal with invalid strings at that
layer, and performance wise it impose a massive overhead.

```
ruby 3.4.2 (2025-02-15 revision d2930f8e7a) +YJIT +PRISM [arm64-darwin24]
Warming up --------------------------------------
             current   504.509k i/100ms
             no_tidy     1.749M i/100ms
Calculating -------------------------------------
             current      5.607M (± 1.0%) i/s  (178.34 ns/i) -     28.253M in   5.038946s
             no_tidy     21.792M (± 0.6%) i/s   (45.89 ns/i) -    110.211M in   5.057658s

Comparison:
             current:  5607354.4 i/s
             no_tidy: 21791597.8 i/s - 3.89x  faster

ruby 3.4.2 (2025-02-15 revision d2930f8e7a) +YJIT +PRISM [arm64-darwin24]
Warming up --------------------------------------
             current   261.902k i/100ms
             no_tidy   518.277k i/100ms
Calculating -------------------------------------
             current      2.795M (± 1.3%) i/s  (357.72 ns/i) -     14.143M in   5.060105s
             no_tidy      5.508M (± 0.2%) i/s  (181.55 ns/i) -     27.987M in   5.081000s

Comparison:
             current:  2795448.7 i/s
             no_tidy:  5508171.9 i/s - 1.97x  faster
```

```ruby
require "bundler/inline"

gemfile do
  gem "rails"
  gem "benchmark-ips"
end

require "active_support/all"
require "active_support/core_ext/erb/util"

module ERB::Util
  def self.html_escape_no_tidy(s) # :nodoc:
    s = s.to_s
    if s.html_safe?
      s
    else
      unwrapped_html_escape(s)
    end
  end
end

Benchmark.ips do |x|
  s = "Hello World"
  x.report("current") { ERB::Util.html_escape(s) }
  x.report("no_tidy") { ERB::Util.html_escape_no_tidy(s) }
  x.compare!(order: :baseline)
end

Benchmark.ips do |x|
  s = "Hello World" * 20
  x.report("current") { ERB::Util.html_escape(s) }
  x.report("no_tidy") { ERB::Util.html_escape_no_tidy(s) }
  x.compare!(order: :baseline)
end
```

Author: byroot

activesupport/lib/active_support/core_ext/erb/util.rb

@@ -12,7 +12,7 @@ def html_escape(s) # :nodoc:
         if s.html_safe?
           s
         else
-          super(ActiveSupport::Multibyte::Unicode.tidy_bytes(s))
+          super(s)
         end
       end
       alias :unwrapped_html_escape :html_escape # :nodoc:
@@ -61,7 +61,7 @@ module Util
     #   html_escape_once('<< Accept & Checkout')
     #   # => "<< Accept & Checkout"
     def html_escape_once(s)
-      ActiveSupport::Multibyte::Unicode.tidy_bytes(s.to_s).gsub(HTML_ESCAPE_ONCE_REGEXP, HTML_ESCAPE).html_safe
+      s.to_s.gsub(HTML_ESCAPE_ONCE_REGEXP, HTML_ESCAPE).html_safe
     end
 
     module_function :html_escape_once

activesupport/test/core_ext/string_ext_test.rb

@@ -1102,12 +1102,6 @@ def to_s
     assert_equal expected, ERB::Util.html_escape(string)
   end
 
-  test "ERB::Util.html_escape should correctly handle invalid UTF-8 strings" do
-    string = "\251 <"
-    expected = "© &lt;"
-    assert_equal expected, ERB::Util.html_escape(string)
-  end
-
   test "ERB::Util.html_escape should not escape safe strings" do
     string = "<b>hello</b>".html_safe
     assert_equal string, ERB::Util.html_escape(string)
@@ -1121,12 +1115,6 @@ def to_s
     assert_equal escaped_string, ERB::Util.html_escape_once(escaped_string)
   end
 
-  test "ERB::Util.html_escape_once should correctly handle invalid UTF-8 strings" do
-    string = "\251 <"
-    expected = "© &lt;"
-    assert_equal expected, ERB::Util.html_escape_once(string)
-  end
-
   test "ERB::Util.xml_name_escape should escape unsafe characters for XML names" do
     unsafe_char = ">"
     safe_char = "Á"