Allowed HTML tags are stripped in gut

[JulioPotier]

Describe the bug
The SCRIPT tag and javascript attributes are stripped from my content when I convert a classic bloc into a gut one.

To Reproduce
Steps to reproduce the behavior:

1. Log in as administrator
2. Add a new classic post and add a <script>alert(gut/)</script> tag + <p onmouseover="javascript:alert('/gut/)">enberg</p> in the content
3. Save
4. Edit it in gutenberg
5. Convert your classic bloc as a gut one

Expected behavior
Since SCRIPT tags and JS attrs are allowed as administrator, gut should not strip them without any notice.

Screenshots
Classic text mode
https://www.dropbox.com/s/ii7b4j26piahj0v/Capture%20d%27%C3%A9cran%202018-08-23%2023.15.31.png?dl=0
Classic visual mode
https://www.dropbox.com/s/bkyw91yeyjuaota/Capture%20d%27%C3%A9cran%202018-08-23%2023.15.46.png?dl=0
Gut after conversion
https://www.dropbox.com/s/6igyvs0xgt7y2bf/Capture%20d%27%C3%A9cran%202018-08-23%2023.16.31.png?dl=0

Desktop (please complete the following information):

• OS: Mac 10.11.6
• Browser: Chrome
• Version 68

Additional context

• Gutenberg 3.6.2

[ZebulanStanphill]

I think this is a duplicate of #6102. See also: #6878 and #7604.

[JulioPotier]

My bad you're right.