processPath(absPath, cache) {
		if (cache[absPath]) {
			return cache[absPath];
		}

		let relPath = path.relative(this.baseDir, absPath);

		if (isWin) {
			relPath = relPath.replace(/\\/g, '/');
		}

		cache[absPath] = relPath;

		return relPath;
	}
Process absolute path and return a shorter one.
@param  {String} absPath
@param  {Object} cache
@return {String}