Make texteffects gm work through serialization and pipe.

Make texteffects gm work through serialization and pipe.

Move Line2DPathEffect (now Sk_) into a separate header file so it can
be shared and initialized.

Switch to the shared version in SampleAll and SampleSlides.

Remove the skip pipe flag from texteffects, since it can now be serialized.

I have a separate change to turn serialization on by default at https://codereview.appspot.com/6498121/

Committed: https://code.google.com/p/skia/source/detail?r=5512

[reed1, 2012-09-12 18:14:49]

Not against this, but those new effects are really just thrown together (a while
ago). Don't want to give the impression to the outside world that they are
"supported" quite yet.

[reed1, 2012-09-12 18:18:32]

lgtm