Browsers such as Chrome and Firefox apply an arbitrary scale to the
current font size if `normal` is used for `line-height`. Firefox uses
1.2 while Chrome uses 1.15. Let's go with the latter for now, it's
relatively easy to change if we ever want to go back on that decision.
This also requires updating the expectations for a lot of layout tests.
The upside of this is that it's a bit easier to compare our layout
results to other browsers', especially Chrome.
When generating line boxes, we place floats simultaneously with the
other items on the same line. The CSS text spec requires us to trim the
whitespace at the end of each line, but we only did so after laying out
all the line boxes.
This changes the way we calculate the current line box width for floats
by subtracting the amount of pixels that the current trailing whitespace
is using.
Fixes#4050.
