src/vs/workbench/services/search/common/ignoreFile.ts/IgnoreFile/gitignoreLinesToExpression
class IgnoreFile:	private gitignoreLinesToExpression(lines: string[], dirPath: string, trimForExclusions: boolean): glob.ParsedExpression {
		const includeLines = lines.map(line => this.gitignoreLineToGlob(line, dirPath));

		const includeExpression: glob.IExpression = Object.create(null);
		for (const line of includeLines) {
			includeExpression[line] = true;
		}

		return glob.parse(includeExpression, { trimForExclusions });
	}