Fix abspos handling of MinMax

abspos used to assume MinMax was border width, not content width.

Annoying part is that we synthesize MinMax out of estimated block_width 
inside ComputeFullAbsoluteWithChildBlockSize.
This now has to be converted to content width adding yet another
layer of if statements in already iffy function.

Bug: 740993
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng
Change-Id: I045e105cad6c684152fca5fe128d924333ee0ccc
Reviewed-on: https://chromium-review.googlesource.com/656312
Commit-Queue: Aleks Totic <atotic@chromium.org>
Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#500676}
3 files changed