Precompile immutable dependencies on "pub get".

sdk/lib/_internal/pub/lib/src/utils.dart

Index: sdk/lib/_internal/pub/lib/src/utils.dart
diff --git a/sdk/lib/_internal/pub/lib/src/utils.dart b/sdk/lib/_internal/pub/lib/src/utils.dart
index 7af41e5f7ec03bef60391c16a6976a58a347ddf8..a3744576020309e72161ee3ec168bae5d2ef076c 100644
--- a/sdk/lib/_internal/pub/lib/src/utils.dart
+++ b/sdk/lib/_internal/pub/lib/src/utils.dart
@@ -264,6 +264,14 @@ Set setMinus(Iterable minuend, Iterable subtrahend) {
   return minuendSet;
 }
 
+/// Returns whether there's any overlap between [set1] and [set2].
+bool overlaps(Set set1, Set set2) {
+  // Iterate through the smaller set.
+  var smaller = set1.length > set2.length ? set1 : set2;
+  var larger = smaller == set1 ? set2 : set1;
+  return smaller.any(larger.contains);
+}
+
 /// Returns a list containing the sorted elements of [iter].
 List ordered(Iterable<Comparable> iter) {
   var list = iter.toList();