fix bug 1208681 - Round down page percentages
fix bug 1208681 - Round down page percentages

When regular rounding is used, sometimes the combined percentage is
above 100% and the browser omits the final status bar (the green one!).
This rounds the percentage down to the nearest 0.1%, which can leave
unused space at the end, but doesn't omit any bars.

mdn/browsercompat,renoirb/browsercompat,mdn/browsercompat,jwhitlock/web-platform-compat,jwhitlock/web-platform-compat,renoirb/browsercompat,mdn/browsercompat,jwhitlock/web-platform-compat,renoirb/browsercompat