Fix browser navigation again

[Hypnosphi]

Issue: #2868

Looks like using pushState in iframe creates new history entries in parent window

[codecov]

Codecov Report

Merging #2870 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master    #2870   +/-   ##
=======================================
  Coverage   35.82%   35.82%           
=======================================
  Files         428      428           
  Lines        9423     9423           
  Branches      975      989   +14     
=======================================
  Hits         3376     3376           
+ Misses       5400     5390   -10     
- Partials      647      657   +10

Impacted Files	Coverage Δ
lib/core/src/client/preview/syncUrlWithStore.js	40.9% <0%> (ø)	⬆️
app/polymer/src/server/config/babel.js	0% <0%> (-100%)	⬇️
...es__/update-addon-info/update-addon-info.output.js	0% <0%> (ø)	⬆️
lib/core/src/client/manager/provider.js	0% <0%> (ø)	⬆️
lib/core/src/client/manager/index.js	0% <0%> (ø)	⬆️
lib/core/src/server/config/env.js	0% <0%> (ø)	⬆️
lib/components/src/table/table.js	83.33% <0%> (ø)	⬆️
lib/ui/src/modules/ui/containers/routed_link.js	22.72% <0%> (ø)	⬆️
lib/core/src/client/manager/preview.js	0% <0%> (ø)	⬆️
addons/a11y/src/components/Report/Item.js	0% <0%> (ø)	⬆️
... and 62 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 4ea7273...850e48d. Read the comment docs.

[tmeasday]

Can confirm this works.

Good job.