Use the already existing strings instead of creating a new one each time
just to test if it responds to the methods.

This reverts commit 8ce3c1e5, reversing
changes made to f93da579.

Reason: It slow down the running time.

require "diffbench"
load 'output_safety.rb'

N = 10000
b = ActiveSupport::SafeBuffer.new("hello world")
DiffBench.bm do
  report "capitalize in safe buffer" do
    N.times do
      b.capitalize
    end
  end
end

> git checkout  069ea45c; diffbench bench.rb;
diffbench bench.rb;diffbench
bench.rb;diffbench bench.rb;diffbench
bench.rb;diffbench bench.rb;diffbench
bench.rb;

Running benchmark with current working tree
Checkout HEAD^
Running benchmark with HEAD^
Checkout to previous HEAD again

                    user     system      total
                    real
----------------------------------capitalize
in safe buffer
After patch:    0.010000   0.000000   0.010000
(  0.009733)
Before patch:   0.010000   0.000000   0.010000
(  0.007702)
Improvement: -26%

Running benchmark with current working tree
Checkout HEAD^
Running benchmark with HEAD^
Checkout to previous HEAD again

                    user     system      total
                    real
----------------------------------capitalize
in safe buffer
After patch:    0.010000   0.000000   0.010000
(  0.009768)
Before patch:   0.010000   0.000000   0.010000
(  0.007896)
Improvement: -24%

Running benchmark with current working tree
Checkout HEAD^
Running benchmark with HEAD^
Checkout to previous HEAD again

                    user     system      total
                    real
----------------------------------capitalize
in safe buffer
After patch:    0.010000   0.000000   0.010000
(  0.009938)
Before patch:   0.010000   0.000000   0.010000
(  0.007768)
Improvement: -28%

Running benchmark with current working tree
Checkout HEAD^
Running benchmark with HEAD^
Checkout to previous HEAD again

                    user     system      total
                    real
----------------------------------capitalize
in safe buffer
After patch:    0.010000   0.000000   0.010000
(  0.010001)
Before patch:   0.010000   0.000000   0.010000
(  0.007873)
Improvement: -27%

Running benchmark with current working tree
Checkout HEAD^
Running benchmark with HEAD^
Checkout to previous HEAD again

                    user     system      total
                    real
----------------------------------capitalize
in safe buffer
After patch:    0.010000   0.000000   0.010000
(  0.009670)
Before patch:   0.010000   0.000000   0.010000
(  0.007800)
Improvement: -24%

Running benchmark with current working tree
Checkout HEAD^
Running benchmark with HEAD^
Checkout to previous HEAD again

                    user     system      total
                    real
----------------------------------capitalize
in safe buffer
After patch:    0.010000   0.000000   0.010000
(  0.009949)
Before patch:   0.010000   0.000000   0.010000
(  0.007752)
Improvement: -28%

https://www.owasp.org/index.php/XSS_%28Cross_Site_Scripting%29_Prevention_Cheat_Sheet#RULE_.231_-_HTML_Escape_Before_Inserting_Untrusted_Data_into_HTML_Element_Content
Closes #7215

This reverts commit fa6d921e.

Reason: Not a fan of such massive changes. We usually close such changes
if made to Rails master as a pull request. Following the same principle
here and reverting.

[ci skip]

For future reference, this is the regex I used: ^\s*#\s*\n(?!\s*#). Replace
with the first match, and voilà! Note that the regex matches a little bit too
much, so you probably want to `git add -i .` and go through every single diff
to check if it actually should be changed.

Logic in clone_empty method was dealing with old @dirty variable, which
has changed by @html_safe in this commit:
https://github.com/rails/rails/commit/139963c99a955520db6373343662e55f4d16dcd1

This was issuing a "not initialized variable" warning - related to:
https://github.com/rails/rails/pull/5237

The logic applied by this method is already handled by the [] override,
so there is no need to reset the variable here.

All the logic is based on the HTML_ESCAPE constant available in
ERB::Util, so it seems more logic to have the entire method there and
just delegate the helper to use it.

        length      user     system      total        real
before  6      0.010000   0.000000   0.010000 (  0.012378)
after   6      0.010000   0.000000   0.010000 (  0.012866)
before  60     0.040000   0.000000   0.040000 (  0.046273)
after   60     0.040000   0.000000   0.040000 (  0.036421)
before  600    0.390000   0.000000   0.390000 (  0.390670)
after   600    0.210000   0.000000   0.210000 (  0.209094)
before  6000   3.750000   0.000000   3.750000 (  3.751008)
after   6000   1.860000   0.000000   1.860000 (  1.857901)

Revert html_escape to do a single gsub again, but add the "n" flag (no
language, i.e. not multi-byte) to protect against XSS via invalid utf8
Signed-off-by: NJosé Valim <jose.valim@gmail.com>

revert the changes from c60995f3 - related to marking sub,gsub as unavailable to use with safe strings