Allow tree artifacts to be omitted, take 2.

PiperOrigin-RevId: 314357168
diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/ArtifactFunctionTest.java b/src/test/java/com/google/devtools/build/lib/skyframe/ArtifactFunctionTest.java
index 8017fef..5607782 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/ArtifactFunctionTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/ArtifactFunctionTest.java
@@ -278,7 +278,7 @@
     omittedOutputs.add(treeFileArtifact2);
 
     SkyValue value = evaluateArtifactValue(artifact2);
-    assertThat(value).isEqualTo(FileArtifactValue.OMITTED_FILE_MARKER);
+    assertThat(value).isEqualTo(TreeArtifactValue.OMITTED_TREE_MARKER);
   }
 
   @Test