Allow unitless values for rootMargin in IntersectionObservers #1885

As a follow-up to #1881 where we allow empty/whitespace strings to mean "0px" as rootMargin for IntersectionObservers, we end up with a confusing situation where "", "0" and 0 all mean 0px, but other unitless values are an error.
Contrary to what one expects, "0" is not treated as a value, but rather as an "allowed error that means 0", i.e.:

0 = 0px
1 = error
"0" = 0px
"1" = error
"" = 0px
" " = 0px
"1px" = 1px

Instead we should just accept unitless values (floats) as pixel values, so it will actually accept 0 1 "0" and "1" as actual values instead of this strange "sometimes but sometimes not".
The standard specification, if I read this correctly, equates unitless absolute dimensions as pixels everywhere, and these kinds of dimensions should be accepted by rootMargin.

As a follow-up to #1881 where we allow empty/whitespace strings to mean "0px" as rootMargin for IntersectionObservers, we end up with a confusing situation where "", "0" and 0 all mean 0px, but other unitless values are an error. Contrary to what one expects, "0" is not treated as a value, but rather as an "allowed error that means 0", i.e.: * 0 = 0px * 1 = error * "0" = 0px * "1" = error * "" = 0px * " " = 0px * "1px" = 1px Instead we should just accept unitless values (floats) as pixel values, so it will actually accept `0` `1` `"0"` and `"1"` as actual values instead of this strange "sometimes but sometimes not". The standard specification, if I read this correctly, equates unitless absolute dimensions as pixels everywhere, and these kinds of dimensions should be accepted by rootMargin.

Test file with added ints and floats. Seems to be OK on the parser side.

rootMargin-intobserver.html

3.5 KiB

Apparently Emilio is all over this one and the main antagonist to common sense.
https://bugzilla.mozilla.org/show_bug.cgi?id=1766163
Spec issue which has been alive for a long time but has been held off: https://github.com/w3c/IntersectionObserver/issues/244

Apparently Emilio is all over this one and the main antagonist to common sense. https://bugzilla.mozilla.org/show_bug.cgi?id=1766163 Spec issue which has been alive for a long time but has been held off: https://github.com/w3c/IntersectionObserver/issues/244

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Allow unitless values for rootMargin in IntersectionObservers #1885