Created attachment 622284 [details]
Testcase: copy and paste this into bugzilla's comment field
Copying and pasting a really long data URI into bugzilla's textarea comment field causing a several seconds long hang.
Selecting it with CTRL+A also causes a several seconds long hang.
1. Download attached file.
2. Copy file's contents to your clipboard.
3. Paste in bugzilla's comment field.
4. Observe hang.
Firefox magically doesn't hang. Possibly by not trying to spellcheck data URIs or some such.
We're spending all of our time in WordSplitState::FindSpecialWord.
Created attachment 622483 [details] [diff] [review]