Add missing @Override of ProgramDefinition#asClass()

Change-Id: Ifff10657da72e9f1e0c019b5b88682309f17dca7
diff --git a/src/main/java/com/android/tools/r8/graph/DexProgramClass.java b/src/main/java/com/android/tools/r8/graph/DexProgramClass.java
index fb50d0e..0ea604e 100644
--- a/src/main/java/com/android/tools/r8/graph/DexProgramClass.java
+++ b/src/main/java/com/android/tools/r8/graph/DexProgramClass.java
@@ -549,6 +549,11 @@
   }
 
   @Override
+  public DexProgramClass asClass() {
+    return this;
+  }
+
+  @Override
   public DexProgramClass asProgramClass() {
     return this;
   }