ENYO-3783: avoid a property appliance on a null object - compatibility required for rc5 version of the library

Related JIRA: https://enyojs.atlassian.net/browse/ENYO-3783

In order to be RC5 compliance, property appliance on a null object must be avoid

Enyo-DCO-1.1-Signed-off-by: Vincent HERILIER vincent.herilier@hp.com