Replace NULL with nullptr

Also fixed some lines that were too long, and a few other minor
details.

Change-Id: I6efba5fb6e03eb5d0a300fddb2a75bf8e2f175cb
diff --git a/runtime/mirror/object_array-inl.h b/runtime/mirror/object_array-inl.h
index 30bc1cd..d473816 100644
--- a/runtime/mirror/object_array-inl.h
+++ b/runtime/mirror/object_array-inl.h
@@ -57,14 +57,14 @@
 inline T* ObjectArray<T>::Get(int32_t i) {
   if (!CheckIsValidIndex(i)) {
     DCHECK(Thread::Current()->IsExceptionPending());
-    return NULL;
+    return nullptr;
   }
   return GetFieldObject<T>(OffsetOfElement(i));
 }
 
 template<class T> template<VerifyObjectFlags kVerifyFlags>
 inline bool ObjectArray<T>::CheckAssignable(T* object) {
-  if (object != NULL) {
+  if (object != nullptr) {
     Class* element_class = GetClass<kVerifyFlags>()->GetComponentType();
     if (UNLIKELY(!object->InstanceOf(element_class))) {
       ThrowArrayStoreException(object);