DevTools: update empty style text on inspected node change

Style sidebar's empty text updates visibility when the filter changes.
It should also update when the inspected node changes.

Bug: 849208
Change-Id: I1f5e2eeb12deecef312fbc9b50f69afd3317ab06
Reviewed-on: https://chromium-review.googlesource.com/1132348
Reviewed-by: Andrey Lushnikov <lushnikov@chromium.org>
Commit-Queue: Erik Luo <luoe@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575541}
2 files changed