Allow disassembling Object class

In platform, disassembling the boot image core jar we crash with a NPE
on the super type when we get to Object

Change-Id: I7bb12c74ee26ed0702d48a54d05087567877999f

src/main/java/com/android/tools/r8/graph/AssemblyWriter.java

diff --git a/src/main/java/com/android/tools/r8/graph/AssemblyWriter.java b/src/main/java/com/android/tools/r8/graph/AssemblyWriter.java
index 75ee123..bcb7abe 100644
--- a/src/main/java/com/android/tools/r8/graph/AssemblyWriter.java
+++ b/src/main/java/com/android/tools/r8/graph/AssemblyWriter.java
@@ -85,7 +85,8 @@
       }
       writeAnnotations(clazz, clazz.annotations(), ps);
       ps.println("# Flags: '" + clazz.accessFlags + "'");
-      if (clazz.superType != application.dexItemFactory.objectType) {
+      if (clazz.superType != application.dexItemFactory.objectType
+          && clazz.getType() != application.dexItemFactory.objectType) {
         ps.println("# Extends: '" + retracer.toSourceString(clazz.superType) + "'");
       }
       for (DexType value : clazz.interfaces.values) {