Add workaround for out_of_range error on older libc++.

Now using std::strtof, which never throws. This will prevent test
failures such as these: http://screen/3eDox3bPe7rBtuy

Change-Id: I67ddd86d4c675886635f36388fba7b0ec3ac3009
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/585746
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Joe Gregorio <jcgregorio@google.com>
2 files changed