Excessive memory/volume consumption for constructed stylesheets shared among shadow DOMs

[danny0838]

Describe the bug
Constructed stylesheets shared among shadow DOMs are duplicated in each HTML representation of shadow DOM during saving a page, causing excessive memory/volume consumption.

To Reproduce
Steps to reproduce the behavior:

1. Go to a thread with many comments under Reddit, e.g. this thread
2. Scroll down and click "View more comments" for around 10+ times.
3. Capture the page with SingleFile.

Expected behavior
The page should be captured normally. Actually the browser is very likely to crash during the capture due to memory exhaustion.

Environment

• OS: Win10 (probably independent)
• Browser: Chrome 126 and Firefox 128 (probably independent)
• Version: 1.22.54

Additional context
See related thread in Stack Exchange

[gildas-lormeau]

Thank you, it's a duplicate of #1387

[gildas-lormeau]

I think I should be able to find a solution at least for self-extracting or ZIP files to de-duplicate stylesheets. I'll try to figure out how to implement this approach.

[gildas-lormeau]

For the record, this issue is due to WICG/webcomponents#939.

[gildas-lormeau]

The size of saved pages on Reddit can be significantly reduced by enabling the option Stylesheets > group duplicate stylesheets together when saving pages in the HTML format. Formats based on ZIP use this optimization without needing to enable this option.