Update smoothscroll detect logic

[bricksroo]

I noticed the smoothscroll polyfill wasn't patching properly in Safari when using the polyfill-service. The first part of the detect logic returns false (indicating the need for the polyfill), while the second returns true. However, when wrapping the detect logic with !() for the ?flags=gated case, it evaluates to false due to the || operator.

This PR updates the logic from || to &&.

Please let me know if there is any more info I can provide or things I forgot to address with this PR.

[CLAassistant]

All committers have signed the CLA.

[JakeChampion]

@bricksroo If the second part of the detect is returning true that means that Safari supports scroll-behaviors. Which version of Safari are you referring to by the way?

We have a long thread in a previous pull-request about why this uses an or operator (||), it is to avoid unnecessarily making the page scroll for browsers which do support scroll-behaviors -- #903

[bricksroo]

@JakeChampion This is in the latest version of safari on macOS.

After a bit more testing, it seems that safari doesn't catch when trying the scrollTo(scrollOptions) with behavior: 'smooth'. It successfully scrolls the element, however without the actual "smooth" behavior. Safari seems to essentially ignore the behavior value of scrollOptions. Here is MDN's live example for ScrollToOptions.

[bricksroo]

Thank you for taking a look. Appreciate you!