Fixes implementation of the following line from the spec:
"However, limit the growth of any fit-content() tracks by their
fit-content() argument."
Now we correctly apply a limit to increased growth limit rather than to
the planned increase.
Change in "Tests/LibWeb/Layout/input/grid/fit-content-2.html" is a
progression and "Item as wide as the content." is actually as wide as a
content.
