[webkit-box] Re-attach layout tree when "-webkit-box" with line-clamp goes horizontal.

In https://chromium-review.googlesource.com/1954925 we added a DCHECK
to ensure that a LayoutDeprecatedFlexibleBox was only having layout
performed when it had "-webkit-box-orient: vertical".

This failed external/wpt/css/css-overflow/webkit-line-clamp-026.html
as we weren't reattaching the layout tree when we had a "-webkit-box"
with "-webkit-line-clamp", which then had its "-webkit-orient" set to
"horizontal".

This patch ensures that we reattach the layout-tree in this case.

Bug: 993813
Change-Id: Ifa176010ce53804fc3d055983564eb126355d4f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1975307Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Christian Biesinger <cbiesinger@chromium.org>
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#726435}

third_party/blink/renderer/core/style/computed_style.cc

@@ -220,11 +220,9 @@ bool ComputedStyle::NeedsReattachLayoutTree(const ComputedStyle* old_style,
   // line-clamping is currently only handled by LayoutDeprecatedFlexibleBox,
   // so that if line-clamping changes then the LayoutObject needs to be
   // recreated.
-  if (new_style->IsDeprecatedWebkitBox() &&
-      (old_style->HasLineClamp() != new_style->HasLineClamp() &&
-       new_style->BoxOrient() == EBoxOrient::kVertical)) {
+  if (old_style->IsDeprecatedFlexboxUsingFlexLayout() !=
+      new_style->IsDeprecatedFlexboxUsingFlexLayout())
     return true;
-  }
   // We need to perform a reattach if a "display: layout(foo)" has changed to a
   // "display: layout(bar)". This is because one custom layout could be
   // registered and the other may not, affecting the box-tree construction.