build(browserstack): initial setup

Closes #4941

scripts/browserstack/waitfor_tunnel.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+
+# Wait for Connect to be ready before exiting
+# Time out if we wait for more than 2 minutes, so that we can print logs.
+let "counter=0"
+
+while [ ! -f $BROWSER_PROVIDER_READY_FILE ]; do
+  let "counter++"
+  if [ $counter -gt 240 ]; then
+    echo "Timed out after 2 minutes waiting for browser provider ready file"
+    # We must manually print logs here because travis will not run
+    # after_script commands if the failure occurs before the script
+    # phase.
+    ./scripts/ci/print-logs.sh
+    exit 5
+  fi
+  sleep .5
+done