src/vs/editor/contrib/folding/intializingRangeProvider.ts/InitializingRangeProvider/compute
class InitializingRangeProvider:	compute(cancelationToken: CancellationToken): Promise<FoldingRegions> {
		let foldingRangeData: IFoldingRangeData[] = [];
		if (this.decorationIds) {
			for (let id of this.decorationIds) {
				let range = this.editorModel.getDecorationRange(id);
				if (range) {
					foldingRangeData.push({ start: range.startLineNumber, end: range.endLineNumber, rank: 1 });
				}
			}
		}
		return Promise.resolve(sanitizeRanges(foldingRangeData, Number.MAX_VALUE));
	}