Ensure source map is not stable if elements kind transitions are expected.

BUG=chromium:700733

Change-Id: Ie937e7064127250b1100109986c3e9b411fae1d6
Reviewed-on: https://chromium-review.googlesource.com/483442Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44780}