Initialize some more variables in SpotShadowTessellator

BUG=skia:6119

Change-Id: Id3a3042df6254e3367713b82f3b08257e0be71b1
Reviewed-on: https://skia-review.googlesource.com/7992
Reviewed-by: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
1 file changed