Revert[2] of add ImageShader, sharing code with its Bitmap cousin

Adjustment from previous land : runtime check for npot-support when texture is requested for tiling.

(patchset #10 id:180001 of https://codereview.chromium.org/1342113002/ )

This reverts commit f2608513626264459a00388537175600b515cae2.

BUG=skia:4365

Review URL: https://codereview.chromium.org/1352293002
9 files changed