Enable new multicol for testing and experimental web platform features.

LayoutTests/VirtualTestSuites

Index: LayoutTests/VirtualTestSuites
diff --git a/LayoutTests/VirtualTestSuites b/LayoutTests/VirtualTestSuites
index 8cbd9ee4ef01d0bae246f956809b255e4bb892b4..c5ce7ca460f99a7a1f02e36fa614f0ca7f3af29e 100644
--- a/LayoutTests/VirtualTestSuites
+++ b/LayoutTests/VirtualTestSuites
@@ -103,6 +103,21 @@
   },
   {
     "prefix": "stable",
+    "base": "compositing/columns",
+    "args": ["--stable-release-mode"]
+  },
+  {
+    "prefix": "stable",
+    "base": "fast/multicol",
+    "args": ["--stable-release-mode"]
+  },
+  {
+    "prefix": "stable",
+    "base": "fast/pagination",
+    "args": ["--stable-release-mode"]
+  },
+  {
+    "prefix": "stable",
     "base": "web-animations-api",
     "args": ["--stable-release-mode"]
   },
@@ -123,25 +138,10 @@
     "args": ["--enable-threaded-compositing"]
   },
   {
-    "prefix": "regionbasedmulticol",
-    "base": "compositing/columns",
-    "args": ["--enable-region-based-columns"]
-  },
-  {
-    "prefix": "regionbasedmulticol",
-    "base": "fast/multicol",
-    "args": ["--enable-region-based-columns"]
-  },
-  {
-    "prefix": "regionbasedmulticol",
-    "base": "fast/pagination",
-    "args": ["--enable-region-based-columns"]
-  },
-  {
     "prefix": "slimmingpaint",
     "base": "fast",
-    "args": ["--enable-slimming-paint", "--enable-region-based-columns", "--enable-blink-features=slimmingPaintUnderInvalidationChecking"],
-    "reference_args": ["--enable-region-based-columns"]
+    "args": ["--enable-slimming-paint", "--enable-blink-features=slimmingPaintUnderInvalidationChecking"],
+    "reference_args": []
   },
   {
     "prefix": "slimmingpaint",