Make pub strong-mode clean.

lib/src/solver/version_solver.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
 import "dart:convert";
 
 import 'package:pub_semver/pub_semver.dart';
 import 'package:stack_trace/stack_trace.dart';
 
@@ skipping 192 matching lines @@
     // See if we cached a failure.
     var error = _versionErrors[package];
     if (error != null) {
       _versionCacheHits++;
       await new Future.error(error.first, error.last);
     }
 
     _versionCacheMisses++;
 
     var source = _cache.source(package.source);
-    var ids;
+    List<PackageId> ids;
     try {
       ids = await source.getVersions(package);
     } catch (error, stackTrace) {
       // If an error occurs, cache that too. We only want to do one request
       // for any given package, successful or not.
       var chain = new Chain.forTrace(stackTrace);
       log.solver("Could not get versions for $package:\n$error\n\n" +
           chain.terse.toString());
       _versionErrors[package] = new Pair(error, chain);
       rethrow;
@@ skipping 113 matching lines @@
   String _describeDependency(PackageDep dep) =>
       "depends on version ${dep.constraint}";
 }
 
 /// Exception thrown when the current SDK's version does not match a package's
 /// constraint on it.
 class BadSdkVersionException extends SolveFailure {
   final String _message;
 
   BadSdkVersionException(String package, String message)
-      : super(package, null),
-        _message = message;
+      : _message = message,
+        super(package, null);
 }
 
 /// Exception thrown when the [VersionConstraint] used to match a package is
 /// valid (i.e. non-empty), but there are no available versions of the package
 /// that fit that constraint.
 class NoVersionException extends SolveFailure {
   final VersionConstraint constraint;
 
   /// The last selected version of the package that failed to meet the new
   /// constraint.
@@ skipping 91 matching lines @@
 
   DependencyNotFoundException(String package, this._innerException,
       Iterable<Dependency> dependencies)
       : super(package, dependencies);
 
   /// The failure isn't because of the version of description of the package,
   /// it's the package itself that can't be found, so just show the name and no
   /// descriptive details.
   String _describeDependency(PackageDep dep) => "";
 }