Fix property lookup in Object.getOwnPropertyDescriptor.

The ecma_op_general_object_get_own_property call does not find all
properties, we need to use the ecma_op_object_get_own_property method
for correct property lookup.

JerryScript-DCO-1.0-Signed-off-by: Peter Gal pgal.u-szeged@partner.samsung.com

tests/jerry/object_get_own_property_descriptor.js

@@ -70,3 +70,16 @@ assert (typeof(desc.set) === 'function');
 assert (desc.configurable);
 assert (desc.enumerable);
 assert (obj.foo === 0)
+
+var array_desc = Object.getOwnPropertyDescriptor(Array, "prototype");
+assert (array_desc.configurable === false);
+assert (array_desc.writable === false);
+assert (array_desc.enumerable === false);
+
+var obj_undef;
+try {
+    Object.getOwnPropertyDescriptor (obj_undef, "fail");
+    assert (false);
+} catch (e) {
+    assert (e instanceof TypeError);
+}