Takes a bit before there is any mention of the thesis's contributions. Jump to section 1.3 on page 10 for a list of goals, then section 1.4 on page 13 for the approach to achieve them.
There is even an explicit section 1.6 "Overview & Contributions", but it's still difficult to discern what specific, scientific contributions were made in this dissertation. The most fruitful place to find clues is in the last paragraph on page 21 which mentions the previous publications “Parsing Expression Grammars Made Practical”, “Taming Context-sensitive Languages with Principled Stateful Parsing” and "Procedural Shift-Reduce Parsing”. So we would probably have to read these papers as well to find out what contribution is supposed to have been made here.