Remove old multicol tests that were only run with the old implementation.

LayoutTests/TestExpectations

 #
 # turn off Slimming Paint tests for all non-Linux platforms...
 crbug.com/453972 [ Mac ] virtual/slimmingpaint/ [ Skip ]
 crbug.com/453972 [ Win ] virtual/slimmingpaint/ [ Skip ]
 crbug.com/453972 [ Android ] virtual/slimmingpaint/ [ Skip ]
 # except for fast/block/, as a sanity test directory.
 crbug.com/453972 [ Mac ] virtual/slimmingpaint/fast/block [ Pass ]
 crbug.com/453972 [ Win ] virtual/slimmingpaint/fast/block [ Pass ]
 crbug.com/453972 [ Android ] virtual/slimmingpaint/fast/block [ Pass ]
 # On linux, run fast/ for the listed sub-directories only.
@@ skipping 1055 matching lines @@
 crbug.com/453002 virtual/antialiasedtext/fast/text/international/text-combine-image-test.html [ NeedsManualRebaseline ]
 crbug.com/454760 virtual/slimmingpaint/fast/text/international/text-combine-image-test.html [ Skip ]
 
 # Expectations changes due to switiching to In-renderer Shared Worker.
 crbug.com/327256 fast/workers/shared-worker-lifecycle.html [ Failure Pass ]
 
 crbug.com/437112 virtual/gpu/fast/canvas/canvas-scale-drawImage-shadow.html [ Pass Failure ]
 
 crbug.com/486830 virtual/slimmingpaint/fast/canvas/canvas-scale-drawImage-shadow.html [ Failure ]
 
-# BEGIN - Old multicol tests that should be removed once the old implementation is gone
-# Imperfect column balancing algorithm in the old implementation:
-crbug.com/408123 fast/multicol/border-padding-pagination.html [ Skip ]
-crbug.com/408123 fast/multicol/vertical-lr/border-padding-pagination.html [ Skip ]
-crbug.com/408123 fast/multicol/vertical-rl/border-padding-pagination.html [ Skip ]
-# CR and ED versions of the multicol spec are contradictory. The new implementation follows the ED. The old follows the CR.
-crbug.com/408123 fast/multicol/column-rules-stacking.html [ Skip ]
-# We have enough non-DRT tests for max-height, so no need for this one.
-crbug.com/408123 fast/multicol/max-height-columns-block.html [ Skip ]
-# These don't test anything unique.
-crbug.com/408123 fast/multicol/span/before-child-anonymous-column-block.html [ Skip ]
-crbug.com/408123 fast/multicol/span/span-as-immediate-child-complex-splitting.html [ Skip ]
-crbug.com/408123 fast/multicol/span/span-as-immediate-child-generated-content.html [ Skip ]
-crbug.com/408123 fast/multicol/span/span-as-immediate-child-property-removal.html [ Skip ]
-crbug.com/408123 fast/multicol/span/span-as-immediate-columns-child-dynamic.html [ Skip ]
-crbug.com/408123 fast/multicol/span/span-as-immediate-columns-child-removal.html [ Skip ]
-crbug.com/408123 fast/multicol/span/span-as-immediate-columns-child.html [ Skip ]
-crbug.com/408123 fast/multicol/span/span-as-nested-columns-child-dynamic.html [ Skip ]
-crbug.com/408123 fast/multicol/span/span-as-nested-columns-child.html [ Skip ]
-# Doesn't render according to the pass condition in the old implementation. Rendered idendically in the new one. Doesn't test anything unique.
-crbug.com/408123 fast/multicol/span/span-as-nested-inline-block-child.html [ Skip ]
-# Rendered correctly (i.e. not in accordance with the invalid pass conditions) in both the old and new implementation. Doesn't test anything unique.
-crbug.com/408123 fast/multicol/span/span-margin-collapsing.html [ Skip ]
-# These are superseded by tests in fast/pagination/
-crbug.com/408123 fast/multicol/pagination-h-horizontal-bt.html [ Skip ]
-crbug.com/408123 fast/multicol/pagination-h-horizontal-tb.html [ Skip ]
-crbug.com/408123 fast/multicol/pagination-h-vertical-lr.html [ Skip ]
-crbug.com/408123 fast/multicol/pagination-h-vertical-rl.html [ Skip ]
-crbug.com/408123 fast/multicol/pagination-v-horizontal-bt.html [ Skip ]
-crbug.com/408123 fast/multicol/pagination-v-horizontal-tb.html [ Skip ]
-crbug.com/408123 fast/multicol/pagination-v-vertical-lr.html [ Skip ]
-crbug.com/408123 fast/multicol/pagination-v-vertical-rl.html [ Skip ]
-
 crbug.com/467477 fast/multicol/vertical-rl/nested-columns.html [ ImageOnlyFailure ]
 crbug.com/467477 virtual/slimmingpaint/fast/multicol/vertical-rl/nested-columns.html [ Skip ]
 
 crbug.com/419101 [ Win Debug ] http/tests/security/contentSecurityPolicy/report-cross-origin-no-cookies.html [ NeedsManualRebaseline ]
 
 crbug.com/374572 svg/dynamic-updates/SVGImageElement-svgdom-preserveAspectRatio-prop.html [ Pass ImageOnlyFailure ]
 
 crbug.com/371654 fast/html/imports/import-custom-element-dup-resolve.html [ Pass Failure ]
 
 crbug.com/394221 [ Mac ] fast/text/emphasis-avoid-ruby.html [ Pass ImageOnlyFailure ]
@@ skipping 630 matching lines @@
 crbug.com/474798 virtual/slimmingpaint/fast/repaint/justify-self-change-keeping-geometry.html [ Skip ]
 
 crbug.com/492084 virtual/stable/webexposed/global-interface-listing-dedicated-worker.html [ NeedsManualRebaseline ]
 crbug.com/492084 virtual/stable/webexposed/global-interface-listing-shared-worker.html [ NeedsManualRebaseline ]
 crbug.com/492084 virtual/stable/webexposed/global-interface-listing.html [ NeedsManualRebaseline ]
 crbug.com/492084 webexposed/global-interface-listing-compositor-worker.html [ NeedsManualRebaseline ]
 crbug.com/492084 webexposed/global-interface-listing-dedicated-worker.html [ NeedsManualRebaseline ]
 crbug.com/492084 webexposed/global-interface-listing-shared-worker.html [ NeedsManualRebaseline ]
 crbug.com/492084 webexposed/global-interface-listing.html [ NeedsManualRebaseline ]