Update to Flutter 1.17.0-3.4.pre (#522)

diff --git a/Dockerfile b/Dockerfile
index 1659db4..b456c0d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -6,7 +6,7 @@
 # To retrieve this value, please run the following in your closest shell:
 #
 # $ (cd flutter && git rev-parse HEAD)
-ARG FLUTTER_COMMIT=0da1ab09224f6c6d69fcff1195a3662fe7ad7534
+ARG FLUTTER_COMMIT=e6b34c2b5c96bb95325269a29a84e83ed8909b5f
 
 # 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 fff0b64..d5b9f7f 100644
--- a/cloud_run.Dockerfile
+++ b/cloud_run.Dockerfile
@@ -6,7 +6,7 @@
 # To retrieve this value, please run the following in your closest shell:
 #
 # $ (cd flutter && git rev-parse HEAD)
-ARG FLUTTER_COMMIT=0da1ab09224f6c6d69fcff1195a3662fe7ad7534
+ARG FLUTTER_COMMIT=e6b34c2b5c96bb95325269a29a84e83ed8909b5f
 
 # We install unzip and remove the apt-index again to keep the
 # docker image diff small.
diff --git a/example/pubspec.lock b/example/pubspec.lock
index ccb6bdf..5e0d649 100644
--- a/example/pubspec.lock
+++ b/example/pubspec.lock
@@ -7,14 +7,14 @@
       name: _fe_analyzer_shared
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.2.0"
+    version: "3.0.0"
   analyzer:
     dependency: transitive
     description:
       name: analyzer
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.39.7"
+    version: "0.39.8"
   archive:
     dependency: transitive
     description:
@@ -70,7 +70,7 @@
       name: build_modules
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.8.1"
+    version: "2.9.0"
   build_resolvers:
     dependency: transitive
     description:
@@ -98,7 +98,7 @@
       name: build_web_compilers
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.9.0"
+    version: "2.10.0"
   built_collection:
     dependency: transitive
     description:
@@ -450,4 +450,4 @@
     source: hosted
     version: "2.2.1"
 sdks:
-  dart: ">=2.7.0 <3.0.0"
+  dart: ">=2.8.0-dev.10.0 <3.0.0"
diff --git a/flutter b/flutter
index 0da1ab0..e6b34c2 160000
--- a/flutter
+++ b/flutter
@@ -1 +1 @@
-Subproject commit 0da1ab09224f6c6d69fcff1195a3662fe7ad7534
+Subproject commit e6b34c2b5c96bb95325269a29a84e83ed8909b5f
diff --git a/pubspec.lock b/pubspec.lock
index 1f53a75..06e0647 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -14,7 +14,7 @@
       name: _fe_analyzer_shared
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.2.0"
+    version: "3.0.0"
   analysis_server_lib:
     dependency: "direct main"
     description:
@@ -28,7 +28,7 @@
       name: analyzer
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.39.7"
+    version: "0.39.8"
   appengine:
     dependency: "direct main"
     description:
@@ -574,7 +574,7 @@
       name: test
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.14.2"
+    version: "1.14.3"
   test_api:
     dependency: transitive
     description:
@@ -588,7 +588,7 @@
       name: test_core
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.3.3"
+    version: "0.3.4"
   timing:
     dependency: transitive
     description:
@@ -644,7 +644,7 @@
       name: webkit_inspection_protocol
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.5.0+1"
+    version: "0.5.1"
   yaml:
     dependency: "direct main"
     description: