parentTranslator in detect calls

Set this.translator for "detect" calls so that parentTranslator is set correctly.

Re http://forums.zotero.org/discussion/27599/zotero-icon-no-longer-appears-in-address-bar-for-univeristy-of-michigan-library-catalogue/ and https://github.com/zotero/translators/commit/51342c4a886b3066b02b389faa0f88a0538e3b2d