Fixing SkTileGrid to clamp rather than clip content and querries that are outside the bounds of the grid

This fix prevents border padding and offsets on the tile grid structure from resulting in bad clipping. The job of clipping contents is left to the playback canvas.

BUG=https://code.google.com/p/skia/issues/detail?id=1209
TEST=TileGrid unit test, 
Review URL: https://codereview.chromium.org/13493016

git-svn-id: http://skia.googlecode.com/svn/trunk@8576 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed