IndexedDB: Zero no longer a valid value for maxCount in getAll().

Prior IDBObjectStore.getAll implementation used zero as the sentinel value
for maxCount to mean unlimited. This change eliminates that check on the
Chrome side. It is now the callers (Blink's) responsibility to pass in a very
large number (MAXUINT) if the intent is to have the response be unbounded.

BUG=457450

Review URL: https://codereview.chromium.org/1138643007

Cr-Commit-Position: refs/heads/master@{#330225}

content/browser/indexed_db/indexed_db_database.cc

@@ -745,9 +745,7 @@ void IndexedDBDatabase::GetAllOperation(
     IndexedDBTransaction* transaction) {
   IDB_TRACE1("IndexedDBDatabase::GetAllOperation", "txn.id", transaction->id());
 
-  DCHECK_GE(max_count, 0);
-  if (!max_count)
-    max_count = std::numeric_limits<decltype(max_count)>::max();
+  DCHECK_GT(max_count, 0);
 
   DCHECK(metadata_.object_stores.find(object_store_id) !=
          metadata_.object_stores.end());