Support other RAWTEXT and PLAINTEXT elements in HTMLParser

[serhiy-storchaka]

Bug report

HTMLParser initially only supported RAWTEXT elements "style" and "script". Then support of RCDATA elements "title" and "textarea" was added in #118350. But there are more RAWTEXT elements: "xmp", "iframe", "noembed", and "noframes".

"noscript" is also switches to the RAWTEXT mode if the scripting flag is enabled.

And the "plaintext" tag switches to the PLAINTEXT state from which there is no exit.

Support of other RAWTEXT elements can be enabled from the user code by adding them to HTMLParser.CDATA_CONTENT_ELEMENTS (this can be done for separate HTMLParser instance), but it would be better to support them by default. "plaintext" needs a special code.

Linked PRs

• gh-137836: Support more RAWTEXT and PLAINTEXT elements in HTMLParser #137837
• [3.14] gh-137836: Support more RAWTEXT and PLAINTEXT elements in HTMLParser (GH-137837) #140841
• [3.13] gh-137836: Support more RAWTEXT and PLAINTEXT elements in HTMLParser (GH-137837) #140842
• [3.12] gh-137836: Support more RAWTEXT and PLAINTEXT elements in HTMLParser (GH-137837) (GH-140842) #140850
• [3.10] gh-137836: Support more RAWTEXT and PLAINTEXT elements in HTMLParser (GH-137837) (GH-140842) #140853
• [3.9] gh-137836: Support more RAWTEXT and PLAINTEXT elements in HTMLParser (GH-137837) (GH-140842) #140857
• [3.13] Fix the versionchanged directive for gh-137836 #140859
• [3.11] gh-137836: Support more RAWTEXT and PLAINTEXT elements in HTMLParser (GH-137837) (GH-140842) #140852