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Changes between Version 4 and Version 5 of Ticket #57301, comment 16

v4	v5
1		For all my testing above, there is one important thing I forgot to test: `'\u{1f170}'` doesn't work in older browsers, as expected, but unfortunately its failure mode is to produce a full-on syntax error. This is difficult to work around, as parsing happens before execution, and thus it's not something we can reasonably expect to feature-detect.
	1	For all my testing above, there is one important thing I forgot to test, and which invalidates some of my earlier points: `'\u{1f170}'` doesn't work in older browsers, as expected, but unfortunately its failure mode is to produce a full-on syntax error. This is difficult to work around, as parsing happens before execution, and thus it's not something we can reasonably expect to feature-detect.
2	2
3	3	This behaviour means that if we were to have `'\u{1f170}'` in the script, then an older browser wouldn't fall back to loading the polyfill, but instead cancel script execution entirely, load nothing, and thus fail to display emoji correctly.