src/vs/editor/common/core/cursorColumns.ts/CursorColumns/visibleColumnFromColumn
class CursorColumns:	public static visibleColumnFromColumn(lineContent: string, column: number, tabSize: number): number {
		const textLen = Math.min(column - 1, lineContent.length);
		const text = lineContent.substring(0, textLen);
		const iterator = new strings.GraphemeIterator(text);

		let result = 0;
		while (!iterator.eol()) {
			const codePoint = strings.getNextCodePoint(text, textLen, iterator.offset);
			iterator.nextGraphemeLength();

			result = this._nextVisibleColumn(codePoint, result, tabSize);
		}

		return result;
	}