LPS-47990  Search shouldn't be executed when "keywords is null" in Search Portlet

... Portlet

The issue was caused by LPS-46416'commit "Apply to search". 

If directly use document.submitForm(), it will skip the form label's onSubmit so that it skips the check "keywords != ''(in 78 line)" to search.

By the way, when onClick is not null, we have added ";" in the end. Please refer to IconTag.getOnClick()

Thanks,
Hai