[graphexplorer] Use an explicit stack in forest compression to prevent JS stack overflow.
[graphexplorer] Use an explicit stack in forest compression to prevent JS stack overflow.

Compare Observatory's object_graph.dart.

TEST=load a large snapshot, such as from dart2js
Change-Id: Ifea2ff4c06f5103d6f1f709fa79183398df90687
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/265404
Reviewed-by: Derek Xu <2c79baefd33c57f83356a155230b34e5a86a2930@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk