src/vs/editor/common/model/textModel.ts/TextModel/getLineFirstNonWhitespaceColumn
class TextModel:	public getLineFirstNonWhitespaceColumn(lineNumber: number): number {
		this._assertNotDisposed();
		if (lineNumber < 1 || lineNumber > this.getLineCount()) {
			throw new Error('Illegal value for lineNumber');
		}
		return this._buffer.getLineFirstNonWhitespaceColumn(lineNumber);
	}