We were numerically overflowing our 16bit coordinates that we communicate
between these two procs. The fixes was in two parts:

1. Just don't draw bitmaps larger than 64K-1 in width or height, since we
   can't represent those coordinates in our transport format (yet).
2. Perform an unsigned shift during the calculation, so we don't get
   sign-extension bleed when packing the two values (X,Y) into our 32bit
   slot.
Review URL: https://codereview.appspot.com/6173046

git-svn-id: http://skia.googlecode.com/svn/trunk@3836 2bbb7eff-a529-9590-31e7-b0007b416f81
4 files changed