SkTileGrid: store insertion order, return results sorted by that.

This removes the need to assume the void* are SkPictureStateTree::Data*.

BUG=skia:
R=robertphillips@google.com, mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/466503002
diff --git a/src/core/SkRecordDraw.cpp b/src/core/SkRecordDraw.cpp
index e075074..0e2a470 100644
--- a/src/core/SkRecordDraw.cpp
+++ b/src/core/SkRecordDraw.cpp
@@ -27,6 +27,7 @@
         SkASSERT(ops.count() == SkToInt(record.count()));
 
         // FIXME: QuadTree doesn't send these back in the order we inserted them.  :(
+        // Also remove the sort in SkPictureData::getActiveOps()?
         if (ops.count() > 0) {
             SkTQSort(ops.begin(), ops.end() - 1, SkTCompareLT<void*>());
         }