convert pathops to use SkSTArray where possible.

convert pathops to use SkSTArray where possible.

Replace SkTDArray with SkTArray and use SkSTArray when
the probable array size is known.

In a couple of places (spans, chases) the arrays are
constructed using insert() so SkTArrays can't be used for
now.

Also, add an optimization to cubic subdivide if either end
is zero or one.

BUG=

Review URL: https://codereview.chromium.org/16951017

git-svn-id: http://skia.googlecode.com/svn/trunk@9635 2bbb7eff-a529-9590-31e7-b0007b416f81