getWhitespaceAccumulatedHeightBeforeLineNumber(lineNumber) {
        this._checkPendingChanges();
        lineNumber = lineNumber | 0;
        const lastWhitespaceBeforeLineNumber = this._findLastWhitespaceBeforeLineNumber(lineNumber);
        if (lastWhitespaceBeforeLineNumber === -1) {
            return 0;
        }
        return this.getWhitespacesAccumulatedHeight(lastWhitespaceBeforeLineNumber);
    }
Returns the accumulated height of whitespaces before the given line number.

@param lineNumber The line number