Fixes for "null instanceof" and class initialization

First issue was that the codegen seemed to expect r0 to contain 0 for
a false result in the null object case. This is a quick fix to make
that true. Given that the code is doing the work of a null check and
pulling out the object's class, the code should probably just pass the
class to the helper function, making this a case of IsAssignableFrom,
not instanceof.

Second issues were related to missing EnsureInitialized calls in two
different code paths, one coming from reflection, one coming from
managed code. New Class::AllocObject assert should help keep us out of
trouble in the future in this area, although perhaps Heap::AllocObject
should have a check as well.

Change-Id: Ib7975b6457481c1ac85135d38f42c6061e6443a0
diff --git a/src/java_lang_Class.cc b/src/java_lang_Class.cc
index 4fe3191..68b83f2 100644
--- a/src/java_lang_Class.cc
+++ b/src/java_lang_Class.cc
@@ -327,7 +327,7 @@
   if (o == NULL) {
     return JNI_FALSE;
   }
-  return Object::InstanceOf(o, c) ? JNI_TRUE : JNI_FALSE;
+  return o->InstanceOf(c) ? JNI_TRUE : JNI_FALSE;
 }
 
 jboolean Class_isInterface(JNIEnv* env, jobject javaThis) {