Add initializer_list support to SkTArray.

Also added unit tests for each of SkTArray's various constructors, and
added `SkTArray::value_type` which allows calling code to refer to the
array's value-type. These unit tests exposed some preexisting strict-
aliasing issues in SkSTArray when compiled on GCC 6+ with optimizations
enabled, which are being investigated separately at skia:10891.

Change-Id: Ia0fb18830cfbbdcb1545fe7f7ac51d8e768a3f94
Bug: skia:10891
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/330279
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
2 files changed