[0.4.7][WIN32SS] Fix BSOD CORE-15433 and repeatedly hit assert CORE-14755

[0.4.7][WIN32SS] Fix BSOD CORE-15433 and repeatedly hit assert CORE-14755

CORE-15433 "Fix assertless BSOD when Opera 12.18 browses duckduckgo.com"
fix ported from 0.4.12-dev-20-g 43e2089 (I ported it back earlier into 0.4.11-RC-7-g 7d0eadd already)

CORE-14775 Allow NULL, Fix repeatedly hit assert when Opera 12.18 browses www.palemoon.org style_name==NULL
by taking parts only of the fix from 0.4.10-dev-284-g ae8762e . I left the verbosed debug-prints aside, as that is not performance-neutral.

They are both related. Actually style_name == NULL is ok, that assert was not correct.
but some of the code was just not handling it properly and dereferenced it.