RenderElement::computeFirstLineStyle returns incorrect style when it is called on the shadow content root first see LayoutTests/imported/w3c/web-platform-tests/css/css-pseudo/first-line-and-placeholder.html with CAN_USE_FIRST_LINE_STYLE_RESOLVE set to 1
<rdar://problem/83675507>
*** This bug has been marked as a duplicate of bug 237362 ***