Bug 1437972 - Fix component associated with WPT css-backgrounds test files. r=jgraham

--HG--
extra : source : bd1571afce38d5f6c5f7c5d476a8a91fbe1b5f35

testing/web-platform/moz.build

@@ -223,7 +223,7 @@ with Files("tests/css/**"):
     BUG_COMPONENT = ("Core", "CSS Parsing and Computation")
 
 with Files("tests/css/css-backgrounds/**"):
-    BUG_COMPONENT = ("Core", "Layout: Text")
+    BUG_COMPONENT = ("Core", "Layout")
 
 with Files("tests/css/css-cascade/**"):
     BUG_COMPONENT = ("Core", "CSS Parsing and Computation")