upload master and alpha docs to different hosts (#10707)

* upload master and alpha docs to different hosts

* include robots.txt when master

dev/bots/docs.sh

@@ -19,13 +19,24 @@ FLUTTER_ROOT=$PWD bin/cache/dart-sdk/bin/dart dev/tools/javadoc.dart
 # Ensure google webmaster tools can verify our site.
 cp dev/docs/google2ed1af765c529f57.html dev/docs/doc
 
-# Upload new API docs when on Travis and branch is master.
-if [ "$TRAVIS_PULL_REQUEST" = "false" ] && [ "$TRAVIS_BRANCH" = "master" ]; then
-  cd dev/docs
-  firebase deploy --project docs-flutter-io
-  exit_code=$?
-  if [[ $exit_code -ne 0 ]]; then
+# Upload new API docs when on Travis
+if [ "$TRAVIS_PULL_REQUEST" == "false" ]; then
+  if [ "$TRAVIS_BRANCH" == "master" -o "$TRAVIS_BRANCH" == "alpha" ]; then
+    cd dev/docs
+
+    if [ "$TRAVIS_BRANCH" == "master" ]; then
+      echo -e "User-agent: *\nDisallow: /" > doc/robots.txt
+      firebase deploy --project master-docs-flutter-io
+    fi
+
+    if [ "$TRAVIS_BRANCH" == "alpha" ]; then
+      firebase deploy --project docs-flutter-io
+    fi
+
+    exit_code=$?
+    if [[ $exit_code -ne 0 ]]; then
       >&2 echo "Error deploying docs via firebase ($exit_code)"
       exit $exit_code
+    fi
   fi
 fi