Fix three strong mode analysis issues.

BUG=https://github.com/dart-lang/pub_semver/issues/10
R=nweiz@google.com

Review URL: https://codereview.chromium.org//1417163006 .

pkgs/pub_semver/CHANGELOG.md

diff --git a/pkgs/pub_semver/CHANGELOG.md b/pkgs/pub_semver/CHANGELOG.md
index 7dca24c..b505230 100644
--- a/pkgs/pub_semver/CHANGELOG.md
+++ b/pkgs/pub_semver/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 1.2.3
+
+* Addressed three strong mode warnings.
+
 # 1.2.2
 
 * Make the package analyze under strong mode and compile with the DDC (Dart Dev

pkgs/pub_semver/lib/src/version_constraint.dart

diff --git a/pkgs/pub_semver/lib/src/version_constraint.dart b/pkgs/pub_semver/lib/src/version_constraint.dart
index dbd0aa5..f84d882 100644
--- a/pkgs/pub_semver/lib/src/version_constraint.dart
+++ b/pkgs/pub_semver/lib/src/version_constraint.dart
@@ -114,7 +114,7 @@
     var compatibleWith = matchCompatibleWith();
     if (compatibleWith != null) return compatibleWith;
 
-    var constraints = [];
+    var constraints = <VersionConstraint>[];
 
     while (true) {
       skipWhitespace();

pkgs/pub_semver/lib/src/version_union.dart

diff --git a/pkgs/pub_semver/lib/src/version_union.dart b/pkgs/pub_semver/lib/src/version_union.dart
index ee9f657..a671514 100644
--- a/pkgs/pub_semver/lib/src/version_union.dart
+++ b/pkgs/pub_semver/lib/src/version_union.dart
@@ -59,7 +59,7 @@
 
     (flattened as List).sort(compareMax);
 
-    var merged = [];
+    var merged = <VersionRange>[];
     for (var constraint in flattened) {
       // Merge this constraint with the previous one, but only if they touch.
       if (merged.isEmpty ||
@@ -132,7 +132,7 @@
 
     // Because both lists of constraints are ordered by minimum version, we can
     // safely move through them linearly here.
-    var newConstraints = [];
+    var newConstraints = <VersionRange>[];
     ourConstraints.moveNext();
     theirConstraints.moveNext();
     while (ourConstraints.current != null && theirConstraints.current != null) {

pkgs/pub_semver/pubspec.yaml

diff --git a/pkgs/pub_semver/pubspec.yaml b/pkgs/pub_semver/pubspec.yaml
index 530a4ce..0ed3e3b 100644
--- a/pkgs/pub_semver/pubspec.yaml
+++ b/pkgs/pub_semver/pubspec.yaml
@@ -1,5 +1,5 @@
 name: pub_semver
-version: 1.2.2
+version: 1.2.3
 author: Dart Team <misc@dartlang.org>
 description: >
  Versions and version constraints implementing pub's versioning policy. This