For computing height in FormattingContext::calculate_intrinsic_sizes
we were calling into BlockFormattingContext::compute_theoretical_height
which will check if the CSS height property was defined and calculate
the height based on that instead of calculating the intrinsic height
This patch adds a new function calculate_intrinsic_height, which will
call into compute_auto_height_for_block_level_element for a block
element, or into compute_height_for_replaced_element for a replaced
element.