Fix missing field initialization in FontPlatformData constructor

Initialize the windows only m_paintTextFlags, m_minSizeForAntiAlias, and
m_useSubpixelPositioning flags in all the FontPlatformData constructors.

R=leviw@chromium.org
BUG=360476

Review URL: https://codereview.chromium.org/227773003

git-svn-id: svn://svn.chromium.org/blink/trunk@170992 bbb929c8-8fbe-4397-9dbb-9b2b20218538