Small cleanups after GrDrawState/GrOptDrawState base class elimination.

Review URL: https://codereview.chromium.org/739133004
a few straggling rebaselines

BUG=skia:

Review URL: https://codereview.chromium.org/742893002
Store DM failures in an array, not a single string.

This should fix the problem where a repeatedly failing test causes this assertion:
  ../../src/core/SkString.cpp:572: failed assertion "length >= 0 && length < SkToInt(kBufferSize)"

Example output:

0 GMs x 7 configs, 2 tests, 0 pictures
0 tasks left, 100 failed
Failures:
  test RTree: ../../tests/RTreeTest.cpp:77	0 != rtree.getCount()
  test RTree: ../../tests/RTreeTest.cpp:77	0 != rtree.getCount()
  test RTree: ../../tests/RTreeTest.cpp:77	0 != rtree.getCount()
  test RTree: ../../tests/RTreeTest.cpp:77	0 != rtree.getCount()
  < 95 lines elided >
  test RTree: ../../tests/RTreeTest.cpp:77	0 != rtree.getCount()
100 failures.

BUG=skia:

Review URL: https://codereview.chromium.org/741833002