Fix value release in ecma_op_is_concat_spreadable (#3346)

Fixes #3356
Fixes #3361

JerryScript-DCO-1.0-Signed-off-by: Adam Szilagyi aszilagy@inf.u-szeged.hu

jerry-core/ecma/operations/ecma-objects.c

@@ -2571,7 +2571,9 @@ ecma_op_is_concat_spreadable (ecma_value_t arg) /**< argument */
 
   if (!ecma_is_value_undefined (spreadable))
   {
-    return ecma_make_boolean_value (ecma_op_to_boolean (spreadable));
+    const bool to_bool = ecma_op_to_boolean (spreadable);
+    ecma_free_value (spreadable);
+    return ecma_make_boolean_value (to_bool);
   }
 
   return (ecma_make_boolean_value (ecma_is_value_array (arg)));

tests/jerry/es2015/regression-test-issue-3356.js

@@ -0,0 +1,19 @@
+// Copyright JS Foundation and other contributors, http://js.foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+var alpha = []; 
+var $ = {[$] : $} 
+obj = {}  
+obj[ Symbol.isConcatSpreadable ] = "\O"  
+alpha.concat(obj)

tests/jerry/es2015/regression-test-issue-3361.js

@@ -0,0 +1,17 @@
+// Copyright JS Foundation and other contributors, http://js.foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+var fakeArray = { [ Symbol ] : 0};
+fakeArray[ Symbol.isConcatSpreadable ] = 2.756;
+[].concat(fakeArray);