Modification of InstanceType enum caused JsonStringifier::Serialize_() function
to consume more stack space (because of a switch statement) in non-optimized
debug build which now causes stack overflow on certain depth of nested objects.
The modification affects neither optimized debug nor release builds.

Change-Id: Ia2925d9abbd1c32c5a4694e14c49b2d0bd119419
Reviewed-on: https://chromium-review.googlesource.com/789074
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49657}