Bump minimum SDK to 2.2.0 (dart-lang/stream_transform#73)

pkgs/stream_transform/.travis.yml

diff --git a/pkgs/stream_transform/.travis.yml b/pkgs/stream_transform/.travis.yml
index e09a3da..e6d16f6 100644
--- a/pkgs/stream_transform/.travis.yml
+++ b/pkgs/stream_transform/.travis.yml
@@ -4,7 +4,6 @@
 dart:
   - dev
   - stable
-  - 2.1.0
 cache:
   directories:
     - $HOME/.pub-cache

pkgs/stream_transform/analysis_options.yaml

diff --git a/pkgs/stream_transform/analysis_options.yaml b/pkgs/stream_transform/analysis_options.yaml
index 6c2853e..82dd7e8 100644
--- a/pkgs/stream_transform/analysis_options.yaml
+++ b/pkgs/stream_transform/analysis_options.yaml
@@ -57,7 +57,7 @@
     - package_names
     - package_prefixed_library_names
     - prefer_adjacent_string_concatenation
-    #- prefer_collection_literals
+    - prefer_collection_literals
     - prefer_conditional_assignment
     - prefer_const_constructors
     - prefer_contains

pkgs/stream_transform/lib/src/combine_latest_all.dart

diff --git a/pkgs/stream_transform/lib/src/combine_latest_all.dart b/pkgs/stream_transform/lib/src/combine_latest_all.dart
index 913c3ce..16f2e80 100644
--- a/pkgs/stream_transform/lib/src/combine_latest_all.dart
+++ b/pkgs/stream_transform/lib/src/combine_latest_all.dart
@@ -66,7 +66,7 @@
       assert(subscriptions == null);
 
       final latestData = List<T>(allStreams.length);
-      final hasEmitted = Set<int>();
+      final hasEmitted = <int>{};
       void handleData(int index, T data) {
         latestData[index] = data;
         hasEmitted.add(index);

pkgs/stream_transform/pubspec.yaml

diff --git a/pkgs/stream_transform/pubspec.yaml b/pkgs/stream_transform/pubspec.yaml
index a681024..d61018e 100644
--- a/pkgs/stream_transform/pubspec.yaml
+++ b/pkgs/stream_transform/pubspec.yaml
@@ -2,11 +2,11 @@
 description: A collection of utilities to transform and manipulate streams.
 author: Dart Team <misc@dartlang.org>
 homepage: https://www.github.com/dart-lang/stream_transform
-version: 0.0.16+1
+version: 0.0.17-dev
 
 environment:
-  sdk: ">=2.1.0 <3.0.0"
+  sdk: ">=2.2.0 <3.0.0"
 
 dev_dependencies:
-  pedantic: ^1.4.0
+  pedantic: ^1.5.0
   test: ^1.0.0