[Telemetry] Fix android unittests that run after testRendererCrash.

Looks like we have to restart the browser if a tab crashes in a browser that
doesn't support tab control.

BUG=337829

Review URL: https://codereview.chromium.org/437443006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@287186 0039d316-1c4b-4281-b951-d872f2087c98

tools/telemetry/telemetry/unittest/tab_test_case.py

@@ -45,6 +45,9 @@ class TabTestCase(unittest.TestCase):
       while len(self._browser.tabs) > 1:
         self._browser.tabs[0].Close()
     else:
+      if not self._browser.tabs:
+        self.tearDownClass()
+        self.setUpClass()
       self._tab = self._browser.tabs[0]
     self._tab.Navigate('about:blank')
     self._tab.WaitForDocumentReadyStateToBeInteractiveOrBetter()