src/vs/base/common/diff/diff.ts/DiffChangeHelper/AddModifiedElement
class DiffChangeHelper:	public AddModifiedElement(originalIndex: number, modifiedIndex: number): void {
		// The 'true' start index is the smallest of the ones we've seen
		this.m_originalStart = Math.min(this.m_originalStart, originalIndex);
		this.m_modifiedStart = Math.min(this.m_modifiedStart, modifiedIndex);

		this.m_modifiedCount++;
	}