[cleanup] Remove FlexBoxIterator from LayoutDeprecatedFlexibleBox. 1/4

Per: https://www.chromestatus.com/feature/5680142707851264

In M85 we switched -webkit-line-clamp over to LayoutNG which had the
(indended) side-effect of removing support for:
 -webkit-box-flex
 -webkit-box-ordinal-group
 -webkit-box-align
 -webkit-box-pack
 -webkit-box-direction

When used with -webkit-line-clamp.

This patch removes the -webkit-box-ordinal-group, and
-webkit-box-direction from legacy by removing the FlexBoxIterator
from LayoutDeprecatedFlexibleBox

Bug: 305376
Change-Id: Ic82f4af9ebd96ef3d859b3dae9dad9d101328333
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2375898Reviewed-by: David Grogan <dgrogan@chromium.org>
Reviewed-by: Christian Biesinger <cbiesinger@chromium.org>
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801873}

third_party/blink/renderer/core/layout/layout_deprecated_flexible_box.h

@@ -27,8 +27,6 @@
 
 namespace blink {
 
-class FlexBoxIterator;
-
 // Handles layout for 'webkit-box' and 'webkit-inline-box'. This class will
 // eventually be replaced by LayoutFlexibleBox.
 class LayoutDeprecatedFlexibleBox final : public LayoutBlock {
@@ -54,7 +52,7 @@ class LayoutDeprecatedFlexibleBox final : public LayoutBlock {
 
   LayoutUnit AllowedChildFlex(LayoutBox* child, bool expanding);
 
-  void ApplyLineClamp(FlexBoxIterator&, bool relayout_children);
+  void ApplyLineClamp(bool relayout_children);
   void ClearLineClamp();
 };