Revert of Allow default font size changing on Linux. (patchset #10 id:180001 of https://codereview.chromium.org/549303004/ )

Reason for revert:
This caused a regression:
https://code.google.com/p/chromium/issues/detail?id=525176

Original issue's description:
> Allow default font size changing on Linux.
>
> Currently base rendering font size on Linux is hardcoded to 16.0 with no possibility of changing it. This patch add such possibility in RendererPreferences.
>
> Webkit part: https://codereview.chromium.org/570243002/
>
> BUG=
>
> Committed: https://crrev.com/f0bc1a926d8f0326ef38b8374e42bc8e244dd2ba
> Cr-Commit-Position: refs/heads/master@{#344746}

TBR=jochen@chromium.org,erg@chromium.org,eseidel@chromium.org,jln@chromium.org,dmazzoni@chromium.org,plundblad@chromium.org,joleksy@opera.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1319613004

Cr-Commit-Position: refs/heads/master@{#345852}
6 files changed