Bug 1903141 Part 1 - Simplify MaybeHasFloats() that checks pushed floats. r=dholbert

After Bug 1902542 Part 5 [1], the pushed floats list is deleted if it is empty.
Therefore, we can simplify `MaybeHasFloats()` as suggested in the XXX comment.

[1] https://hg.mozilla.org/mozilla-central/rev/52a9610fc9f2

Differential Revision: https://phabricator.services.mozilla.com/D214044

layout/generic/nsBlockFrame.cpp

@@ -1224,6 +1224,18 @@ bool nsBlockFrame::IsInLineClampContext() const {
   return false;
 }
 
+bool nsBlockFrame::MaybeHasFloats() const {
+  if (!mFloats.IsEmpty()) {
+    return true;
+  }
+  if (HasPushedFloats()) {
+    return true;
+  }
+  // For the OverflowOutOfFlowsProperty I think we do enforce that, but it's
+  // a mix of out-of-flow frames, so that's why the method name has "Maybe".
+  return HasAnyStateBits(NS_BLOCK_HAS_OVERFLOW_OUT_OF_FLOWS);
+}
+
 /**
  * Iterator over all descendant inline line boxes, except for those that are
  * under an independent formatting context.

layout/generic/nsBlockFrame.h

@@ -667,20 +667,7 @@ class nsBlockFrame : public nsContainerFrame {
    * @return false iff this block does not have a float on any child list.
    * This function is O(1).
    */
-  bool MaybeHasFloats() const {
-    if (!mFloats.IsEmpty()) {
-      return true;
-    }
-    // XXX this could be replaced with HasPushedFloats() if we enforced
-    // removing the property when the frame list becomes empty.
-    nsFrameList* list = GetPushedFloats();
-    if (list && !list->IsEmpty()) {
-      return true;
-    }
-    // For the OverflowOutOfFlowsProperty I think we do enforce that, but it's
-    // a mix of out-of-flow frames, so that's why the method name has "Maybe".
-    return HasAnyStateBits(NS_BLOCK_HAS_OVERFLOW_OUT_OF_FLOWS);
-  }
+  bool MaybeHasFloats() const;
 
  protected:
   /** grab overflow lines from this block's prevInFlow, and make them