Intermittent unit test failure - mozilla.components.support.webextensions.WebExtensionSupportTest - reacts to custom tab being closed by removing tab from store

[Archaeopteryx]

Firebase Test Run:

https://treeherder.mozilla.org/logviewer?job_id=382855265&repo=android-components

Stacktrace:

  TEST: reacts to custom tab being closed by removing tab from store
  FAILURE

java.lang.IllegalStateException: Dispatchers.Main is used concurrently with setting it
	at kotlinx.coroutines.test.internal.TestMainDispatcher$NonConcurrentlyModifiable.concurrentRW(TestMainDispatcher.kt:70)
	at kotlinx.coroutines.test.internal.TestMainDispatcher$NonConcurrentlyModifiable.setValue(TestMainDispatcher.kt:86)
	at kotlinx.coroutines.test.internal.TestMainDispatcher.resetDispatcher(TestMainDispatcher.kt:40)
	at kotlinx.coroutines.test.TestDispatchers.resetMain(TestDispatchers.kt:37)
	at mozilla.components.support.test.rule.MainCoroutineRule.finished(MainCoroutineRule.kt:53)
	at org.junit.rules.TestWatcher.finishedQuietly(TestWatcher.java:117)
	at org.junit.rules.TestWatcher.access$400(TestWatcher.java:46)
	at org.junit.rules.TestWatcher$1.evaluate(TestWatcher.java:64)
	at org.junit.rules.RunRules.evaluate(RunRules.java:20)
	at org.robolectric.RobolectricTestRunner$HelperTestRunner$1.evaluate(RobolectricTestRunner.java:591)
	at org.robolectric.internal.SandboxTestRunner$2.lambda$evaluate$0(SandboxTestRunner.java:274)
	at org.robolectric.internal.bytecode.Sandbox.lambda$runOnMainThread$0(Sandbox.java:88)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)
	Suppressed: org.robolectric.android.internal.AndroidTestEnvironment$UnExecutedRunnablesException: Main looper has queued unexecuted runnables. This might be the cause of the test failure. You might need a shadowOf(Looper.getMainLooper()).idle() call.

Build:

https://github.com/mozilla-mobile/android-components/commit/6e52770395578f7fa9f6064770566e49c5e1c3b7

┆Issue is synchronized with this Jira Task