Update to Dart 2.9.2, revert Flutter to previous beta (#582)

diff --git a/.gitpod.Dockerfile b/.gitpod.Dockerfile
index 3e0fe61..7674375 100644
--- a/.gitpod.Dockerfile
+++ b/.gitpod.Dockerfile
@@ -6,8 +6,8 @@
 # More information: https://www.gitpod.io/docs/config-docker/
 
 RUN sudo apt-get update && \
-    wget https://storage.googleapis.com/dart-archive/channels/stable/release/2.9.1/linux_packages/dart_2.9.1-1_amd64.deb && \
-    sudo dpkg -i dart_2.9.1-1_amd64.deb && \
+    wget https://storage.googleapis.com/dart-archive/channels/stable/release/2.9.2/linux_packages/dart_2.9.2-1_amd64.deb && \
+    sudo dpkg -i dart_2.9.2-1_amd64.deb && \
     sudo apt-get install -y protobuf-compiler redis && \
     sudo apt-get update && \
     echo "export PATH=\"\$PATH:/usr/lib/dart/bin:\$HOME/.pub-cache/bin\"" >> $HOME/.bashrc && \
diff --git a/.travis.yml b/.travis.yml
index d0688fc..3fe8380 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,7 +3,7 @@
   - gem install coveralls-lcov
 dart:
   # Keep this value aligned with min SDK value in pubspec.yaml and FROM line of Dockerfile
-  - "2.9.1"
+  - "2.9.2"
   # 2.10 is currently breaking dart services. Tracking bug: https://github.com/dart-lang/dart-pad/issues/1616
   # - beta
 
diff --git a/Dockerfile b/Dockerfile
index 0953b60..ddd6aac 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,12 +1,12 @@
 # Keep aligned with min SDK in pubspec.yaml and Dart test version in .travis.yml
-FROM google/dart:2.9.1
+FROM google/dart:2.9.2
 
 # The specific commit that dart-services should use. This should be kept
 # in sync with the flutter submodule in the dart-services repo.
 # To retrieve this value, please run the following in your closest shell:
 #
 # $ (cd flutter && git rev-parse HEAD)
-ARG FLUTTER_COMMIT=be9bc8cb3942bda5d8ef4e44b44616c470625e18
+ARG FLUTTER_COMMIT=916c3ac648aa0498a70f32b5fc4f6c51447628e3
 
 # We install unzip and remove the apt-index again to keep the
 # docker image diff small.
diff --git a/cloud_run.Dockerfile b/cloud_run.Dockerfile
index a898a69..3908e93 100644
--- a/cloud_run.Dockerfile
+++ b/cloud_run.Dockerfile
@@ -1,12 +1,12 @@
 # Keep aligned with min SDK in pubspec.yaml and Dart test version in .travis.yml
-FROM google/dart:2.9.1
+FROM google/dart:2.9.2
 
 # The specific commit that dart-services should use. This should be kept
 # in sync with the flutter submodule in the dart-services repo.
 # To retrieve this value, please run the following in your closest shell:
 #
 # $ (cd flutter && git rev-parse HEAD)
-ARG FLUTTER_COMMIT=be9bc8cb3942bda5d8ef4e44b44616c470625e18
+ARG FLUTTER_COMMIT=916c3ac648aa0498a70f32b5fc4f6c51447628e3
 
 # We install unzip and remove the apt-index again to keep the
 # docker image diff small.
diff --git a/flutter b/flutter
index be9bc8c..916c3ac 160000
--- a/flutter
+++ b/flutter
@@ -1 +1 @@
-Subproject commit be9bc8cb3942bda5d8ef4e44b44616c470625e18
+Subproject commit 916c3ac648aa0498a70f32b5fc4f6c51447628e3
diff --git a/pubspec.lock b/pubspec.lock
index 5a77ebb..0fcb15c 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -646,4 +646,4 @@
     source: hosted
     version: "2.2.1"
 sdks:
-  dart: ">=2.9.0 <3.0.0"
+  dart: ">=2.9.2 <3.0.0"
diff --git a/pubspec.yaml b/pubspec.yaml
index ceb4aea..aee9427 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -3,7 +3,7 @@
 
 environment:
   # Keep SDK aligned with .travis.yml and FROM line of Dockerfile
-  sdk: ^2.9.0
+  sdk: ^2.9.2
 
 dependencies:
   analyzer: ^0.39.15