Previously, the column count was always incremented by 1. This led to a
mismatch with `compute_outer_content_sizes()`, which did use the `span`
attribute to advance the column index. This mismatch caused an
out-of-bounds access when the column index was greater than the
expected number of columns.
Inline nodes in our layout tree have a position, so let's show it. By
centralizing the logic for this, block nodes now lose their redundant
'content-size' dump info which is already part of the box model dump.
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.
This code previously only allocated enough space in
m_col_elements_by_index for 1 slot per column, meaning that columns
with a span > 1 would write off the end of it.
