HTML API: Skip over contents of RAWTEXT elements such as STYLE.

[dmsnell]

When encountering elements that imply switching into the RAWTEXT parsing state, the Tag Processor should skip processing until existing the RAWTEXT state.

In this patch the Tag Processor does just that, except for the case of the deprecated XMP element which implies further and more complicated rules.

There's an implicit assumption that the SCRIPT ENABLED flag in HTML parsing is enabled so that the contents of NOSCRIPT can be skipped. Otherwise, it would be required to parse the contents of that tag.

Trac Ticket: #59292

When encountering elements that imply switching into the RAWTEXT parsing state, the Tag Processor should skip processing until existing the RAWTEXT state.

In this patch the Tag Processor does just that, except for the case of the deprecated XMP element which implies further and more complicated rules.

There's an implicit assumption that the SCRIPT ENABLED flag in HTML parsing is enabled so that the contents of NOSCRIPT can be skipped. Otherwise, it would be required to parse the contents of that tag.

_This was not a reported bug; it was discovered through the Core unit test cases for kses_

[Bernhard Reiter]

In 56563:

HTML API: Skip over contents of RAWTEXT elements such as STYLE.

When encountering elements that imply switching into the RAWTEXT parsing state,
the Tag Processor should skip processing until exiting the RAWTEXT state.

In this patch the Tag Processor does just that, except for the case of the
deprecated XMP element which implies further and more complicated rules.

There's an implicit assumption that the SCRIPT ENABLED flag in HTML parsing
is enabled so that the contents of NOSCRIPT can be skipped. Otherwise, it would
be required to parse the contents of that tag.

Props dmsnell.
Fixes #59292.

Committed to Core trunk in https://core.trac.wordpress.org/changeset/56563.

[Bernhard Reiter]

Reopening for backport to 6.3.

[Bernhard Reiter]

In 56564:

HTML API: Skip over contents of RAWTEXT elements such as STYLE.

When encountering elements that imply switching into the RAWTEXT parsing state,
the Tag Processor should skip processing until exiting the RAWTEXT state.

In this patch the Tag Processor does just that, except for the case of the
deprecated XMP element which implies further and more complicated rules.

There's an implicit assumption that the SCRIPT ENABLED flag in HTML parsing
is enabled so that the contents of NOSCRIPT can be skipped. Otherwise, it would
be required to parse the contents of that tag.

Props dmsnell.
Merges [56563] to the 6.3 branch.
Fixes #59292.

Backported to Core's 6.3 branch in https://core.trac.wordpress.org/changeset/56564.