Revert of Remove Mac native font type members from FontPlatformData

Revert of Remove Mac native font type members from FontPlatformData (patchset #11 id:200001 of https://codereview.chromium.org/879533003/)

Reason for revert:
The patch broke the Mac GN builder, preventing the roll:

ERROR at //third_party/WebKit/Source/platform/BUILD.gn:221:7: Item not found
      "fonts/skia/FontCustomPlatformDataSkia.cpp",

It may have also caused some failures on Mac.

Original issue's description:
> Remove Mac native font type members from FontPlatformData
> 
> FontPlatformData keeps several Mac specific font members 
> around, NSFont, ctFont, cgFont, while all other platforms
> rely on just using an SkTypeface. This leads to a lot of 
> ifdefs in the code, confusion about which member is currently
> instantiated and a history of null-dereference crashes on Mac
> due to hard to track failures of font instantiation.
> 
> After we got access to a CTFont object from an
> SkTypeface for compatibility with HarfBuzz AAT shaping and
> clipboard text export [1], I suggest to remove the native 
> handles and focus on using SkTypefaces. This allows us as 
> well to remove a lot of mostly redundant platform-specific
> code on Mac.
> 
> [1] https://codereview.chromium.org/872963003/
> 
> BUG=414234
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=192506

TBR=eae@chromium.org,rsesek@chromium.org,kbr@chromium.org,japhet@chromium.org,pfeldman@chromium.org,tkent@chromium.org,alph@chromium.org,dominik.rottsches@intel.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=414234
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=192544

[Julien - ping for review, 2015-03-25 15:33:43]

Created Revert of Remove Mac native font type members from FontPlatformData

[commit-bot: I haz the power, 2015-03-25 15:34:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1021483004/1

[Julien - ping for review, 2015-03-25 15:34:15]

The CQ bit was unchecked by jchaffraix@chromium.org

[commit-bot: I haz the power, 2015-03-25 15:34:29]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-03-25 15:34:43]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=192544

[Julien - ping for review, 2015-03-25 15:51:01]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1022663004/ by jchaffraix@chromium.org.

The reason for reverting is: Loislo and Dominik handled this in a better way.
For some reason, the "cancel commit" didn't work (or /me didn't)..