[tools] Reduce grokdump output size

Minidumps have gotten bigger stack ranges leading to long load times when using
grokdump's web interface. A major factor seems to be the output size of the
generated table. Using shorter class names and avoiding quotes for most
attributes we can get a significant size reduction.

BUG=

Review-Url: https://codereview.chromium.org/2352303002
Cr-Commit-Position: refs/heads/master@{#39589}