Created attachment 434077 [details] test case See attached test case. In Blink and Gecko, all three white-space settings produce the same result. In WebKit, the first setting (white-space: pre-wrap) produces a different layout when an inline element is added.
This only affects legacy layout; LFC works correctly.
It looks like we drop the word-break property for the rest of the content when we see an inline box (unless it is explicitly set on the content again e.g. <div style='white-space: pre-wrap'><b>asdf</b> <span style="word-break: break-all">alsdjfalk</span></div>)
<rdar://problem/81317182>