Add external/wpt/css/CSS2/floats-clear LayoutNG virtual test suite.

third_party/WebKit/LayoutTests/VirtualTestSuites

Index: third_party/WebKit/LayoutTests/VirtualTestSuites
diff --git a/third_party/WebKit/LayoutTests/VirtualTestSuites b/third_party/WebKit/LayoutTests/VirtualTestSuites
index ddbf7d97a209cc30d4e7afe629dd6b40f5c755cc..4fae130748957047efdc72719adc4f5fe506c673 100644
--- a/third_party/WebKit/LayoutTests/VirtualTestSuites
+++ b/third_party/WebKit/LayoutTests/VirtualTestSuites
@@ -483,6 +483,11 @@
     "args": ["--enable-blink-features=LayoutNG"]
   },
   {
+    "prefix": "layout_ng",
+    "base": "external/wpt/css/CSS2/floats-clear",
+    "args": ["--enable-blink-features=LayoutNG"]
+  },
+  {
     "prefix": "feature-policy",
     "base": "http/tests/feature-policy",
     "args": ["--enable-blink-features=FeaturePolicy"]