Having reviewed the changelogs and actual changes here https://github.com/dompdf/dompdf/releases and following a run-test on this I can't find any broken functionality as a result of this upgrade.
There are numerous fixes and improvements in this and the next planned version 1.0.3 will further improve SVG handling.
"require": {
"php": "~7.2",
"cache/integration-tests": "~0.17.0",
- "dompdf/dompdf" : "~0.8",
+ "dompdf/dompdf" : "~1.0.0",
"firebase/php-jwt": ">=3 <6",
"electrolinux/phpquery": "^0.9.6",
"symfony/config": "~3.0 || ~4.4",