ec6e7303dd
This is the result of running
```sh
find ./ -iname "*.png" -exec pngcrush -brute -ow -- {} \;
```
[Summary of size reductions](https://docs.google.com/spreadsheets/d/12Qgx7DfKabWw0PJza6ozC1kCHTofi6wyBLWGtwLW7G4/preview)
Last done in July, 2017 in #18243
PR Close #28479
