function initGlobalPreprocessorsRegistry(sType, sViewType) {
		if (!View._mPreprocessors[sViewType]) {
			View._mPreprocessors[sViewType] = {};
		}
		if (!View._mPreprocessors[sViewType][sType]) {
			View._mPreprocessors[sViewType][sType] = [];
		}
	}
Executes preprocessors for a type of source

@param {string} sType
  the type of preprocessor, e.g. "raw", "xml" or "controls"
@param {object|string|Element} vSource
  the view source as a JSON object, a raw text, an XML document element or a Promise resolving with those
@param {boolean} [bSync]
  describes the view execution, true if sync
@returns {Promise|object|string|Element}
  a promise resolving with the processed source or an error | the source when bSync=true
@protected