src/vs/base/common/diff/diff.ts/LcsDiff/_ModifiedRegionIsBoundary
class LcsDiff:	private _ModifiedRegionIsBoundary(modifiedStart: number, modifiedLength: number): boolean {
		if (this._ModifiedIsBoundary(modifiedStart) || this._ModifiedIsBoundary(modifiedStart - 1)) {
			return true;
		}
		if (modifiedLength > 0) {
			const modifiedEnd = modifiedStart + modifiedLength;
			if (this._ModifiedIsBoundary(modifiedEnd - 1) || this._ModifiedIsBoundary(modifiedEnd)) {
				return true;
			}
		}
		return false;
	}