Flaky heapdump pummel test

[trevnorris]

Right now test/pummel/test-heapdump-worker.js is being skipped on asan builds because it sometimes fails showing indrect leaks. To demonstrate this the test will need to be edited to remove the process.config.variables.asan check. Then do the following:

./configure --enable-asan
make -j16
for i in $(seq 1 16); do ./out/Release/nsolid --expose-internals test/pummel/test-heapdump-worker.js & done

I assume this is a timing issue because it's harder to get the same failure if using both --debug and --enable-asan. It also only shows up if validating the snapshot then running worker.terminate(). Removing the validateSnapshotNodes() call and replacing it with a busy loop will also not trigger the issue.