Bug 1178806. IndexedDB autoincrement overflow should be throwing ConstraintError per spec. r=bent

dom/indexedDB/ActorsParent.cpp

@@ -23070,8 +23070,7 @@ ObjectStoreAddOrPutRequestOp::DoDatabaseWork(DatabaseConnection* aConnection)
       MOZ_ASSERT(autoIncrementNum > 0);
 
       if (autoIncrementNum > (1LL << 53)) {
-        IDB_REPORT_INTERNAL_ERR();
-        return NS_ERROR_DOM_INDEXEDDB_UNKNOWN_ERR;
+        return NS_ERROR_DOM_INDEXEDDB_CONSTRAINT_ERR;
       }
 
       key.SetFromInteger(autoIncrementNum);

testing/web-platform/meta/IndexedDB/keygenerator-overflow.htm.ini

@@ -1,5 +0,0 @@
-[keygenerator-overflow.htm]
-  type: testharness
-  [Keygenerator overflow]
-    expected: FAIL
-