fix issue related to xscale when log scale is set

[gilbertogalvis]

This PR fix a issue when log scale is set on axes.

Example code

gapminderDataFiveYear = readtable('https://raw.githubusercontent.com/plotly/datasets/master/gapminderDataFiveYear.csv');

year = 0;
if year == 0
    year = min(gapminderDataFiveYear.year);
end

YEAR = year;
rows = (gapminderDataFiveYear.year == YEAR);
subtab = gapminderDataFiveYear(rows,:);
scatter(subtab.gdpPercap, ...
    subtab.lifeExp, ...
    subtab.pop/100000, ...
    categorical(subtab.country), 'filled');

%set(gca,'FontSize',14);
%xlabel(gca, 'gdpPercap');
%ylabel(gca, 'lifeExp');  
set(gca,'xscale','log');

fig = fig2plotly(gcf, 'offline', true, 'open', false, 'Visible', false);
response = plotlyoffline(fig);

web(response, '-browser');

Result: