Properly disable multicol when specified on form controls.

A test broke recently, in crrev.com/2300902

Now that file upload controls are implemented as regular blocks, the
LayoutObject type check won't do anymore.

Bug: 829028,1040826
Change-Id: I37170f518bcc818a2f4c28c8064777c1c1df5831
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2421453Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809056}

third_party/blink/renderer/core/layout/layout_block_flow.cc

@@ -4396,9 +4396,10 @@ void LayoutBlockFlow::CreateOrDestroyMultiColumnFlowThreadIfNeeded(
   if (IsFieldsetIncludingNG())
     return;
 
-  // Form controls are replaced content, and are therefore not supposed to
-  // support multicol.
-  if (IsFileUploadControl() || IsTextControl() || IsListBox(this))
+  // Form controls are replaced content (also when implemented as a regular
+  // block), and are therefore not supposed to support multicol.
+  const auto* element = DynamicTo<Element>(GetNode());
+  if (element && element->IsFormControlElement())
     return;
 
   // We don't allow custom layout and multicol on the same object. This is

third_party/blink/web_tests/TestExpectations

@@ -1080,7 +1080,6 @@ crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/dynamic/relpos-becom
 crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/dynamic/remove-column-content-next-to-abspos-between-spanners.html [ Failure ]
 crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/dynamic/static-becomes-relpos-has-abspos.html [ Failure ]
 crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/event-offset-in-nested.html [ Failure ]
-crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/file-upload-as-multicol.html [ Failure ]
 crbug.com/1061423 virtual/layout_ng_block_frag/fast/multicol/flipped-blocks-hit-test.html [ Failure ]
 crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/float-margin-at-row-boundary.html [ Failure ]
 crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/float-margin-at-row-boundary-fixed-multicol-height.html [ Failure ]