Revert "remove broken platforms"

This reverts commit a5acdb3e06170663f74b01e7d19f95000f0e6091.
diff --git a/.travis.yml b/.travis.yml
index 9da8ab5..b020f5b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -48,10 +48,15 @@
       <<: *_ios
 
     # many tests with saucelabs
+    - env: PLATFORM=browser-chrome
     - env: PLATFORM=browser-firefox
     - env: PLATFORM=browser-safari
     - env: PLATFORM=browser-edge
 
+    - env: PLATFORM=ios-11.3
+      <<: *_ios
+    - env: PLATFORM=ios-12.0
+      <<: *_ios
     - env: PLATFORM=ios-12.2
       <<: *_ios