Bug 1695314 - Frame constructor shouldn't use nsIFrame::IsFloating to determine whether it should create a float. r=TYLin

It should just look at the float style. This shouldn't be a behavior
change because SVG text should pass false for aCanBeFloated.

This unblocks bug 1690701 because checking the out of flow frame bit
here would be wrong (we're deciding whether the frame should be out of
flow so the bit isn't set yet).

Differential Revision: https://phabricator.services.mozilla.com/D106664

layout/base/nsCSSFrameConstructor.cpp

@@ -1045,13 +1045,13 @@ AbsoluteFrameList* nsFrameConstructorState::GetOutOfFlowFrameList(
     return &mPopupList;
   }
 #endif  // MOZ_XUL
-  if (aCanBeFloated && aNewFrame->IsFloating()) {
+  const nsStyleDisplay* disp = aNewFrame->StyleDisplay();
+  if (aCanBeFloated && disp->IsFloatingStyle()) {
     *aPlaceholderType = PLACEHOLDER_FOR_FLOAT;
     return &mFloatedList;
   }
 
   if (aCanBePositioned) {
-    const nsStyleDisplay* disp = aNewFrame->StyleDisplay();
     if (disp->mTopLayer != StyleTopLayer::None) {
       *aPlaceholderType = PLACEHOLDER_FOR_TOPLAYER;
       if (disp->mPosition == StylePositionProperty::Fixed) {