Unfortunately not. I tried different approaches, but they all failed, because GWT depends on Jetty 8.
The most promising approach was to not package Jetty in gwt-dev at all, and maintain two different
codeserver versions targeting Jetty 8 & Jetty 9. And by not shipping asm library in gwt-dev.jar in 2.7
was steps in the same direction. While viable option, this approach was abandoned, after codeserver
itself was shipped in gwt-dev.jar.
While all "straight forward" ways to get GWT + SDM + Jetty9 up and running failed, there is a hack:
1. strip outdated Jetty 8 from gwt-dev.jar
2. add dependency to Jetty 9
3. replace one source file from codeserver with this version [1]
See these changes for glory details [2], [3].