Revert "Use native async/await support in pub."

sdk/lib/_internal/pub_generated/lib/src/solver/dependency_queue.dart

Index: sdk/lib/_internal/pub_generated/lib/src/solver/dependency_queue.dart
diff --git a/sdk/lib/_internal/pub/lib/src/solver/dependency_queue.dart b/sdk/lib/_internal/pub_generated/lib/src/solver/dependency_queue.dart
similarity index 94%
copy from sdk/lib/_internal/pub/lib/src/solver/dependency_queue.dart
copy to sdk/lib/_internal/pub_generated/lib/src/solver/dependency_queue.dart
index b2152477304323d2226515fee0ee5b6b375fd9f7..07fdbc45c3786dee2952967394d917afb30aaa4d 100644
--- a/sdk/lib/_internal/pub/lib/src/solver/dependency_queue.dart
+++ b/sdk/lib/_internal/pub_generated/lib/src/solver/dependency_queue.dart
@@ -49,8 +49,8 @@ class DependencyQueue {
   /// This will only be non-null while a sort is in progress.
   Future _sortFuture;
 
-  factory DependencyQueue(BacktrackingSolver solver,
-      Iterable<PackageDep> deps) {
+  factory DependencyQueue(BacktrackingSolver solver, Iterable<PackageDep> deps)
+      {
     // Separate out the presorted ones.
     var presorted = <PackageDep>[];
     var remaining = <PackageDep>[];
@@ -69,7 +69,9 @@ class DependencyQueue {
     // deterministic.
     presorted.sort((a, b) => a.name.compareTo(b.name));
 
-    return new DependencyQueue._(solver, new Queue<PackageDep>.from(presorted),
+    return new DependencyQueue._(
+        solver,
+        new Queue<PackageDep>.from(presorted),
         remaining);
   }
 
@@ -136,8 +138,8 @@ class DependencyQueue {
       // don't meet it.
       for (var rootDep in _solver.root.immediateDependencies) {
         if (rootDep.name == dep.name) {
-          versions = versions.where(
-              (id) => rootDep.constraint.allows(id.version));
+          versions =
+              versions.where((id) => rootDep.constraint.allows(id.version));
           break;
         }
       }