Added class AutoFragmentChildProcAdvance to be constructed before a child emitCode...

Added class AutoFragmentChildProcAdvance to be constructed before a child emitCode and destructed after

Fixed wrong indent

Changed auto child advance back to backwards linear search for getting subset of coords and samplers array of a child

Used offset from parent instead of backwards linear search to find a child proc's coords and transforms in Auto...Advance

append mangleString to variable name in nameVariable()

BUILDS! Added AutoFragmentChildProcAdvance class; fixed a few errors from previous commits

BUG=skia:4182

Review URL: https://codereview.chromium.org/1286293002