Added full js & js_util packages

packages/quiver_iterables/lib/src/count.dart

Index: packages/quiver_iterables/lib/src/count.dart
diff --git a/packages/quiver/lib/src/iterables/concat.dart b/packages/quiver_iterables/lib/src/count.dart
similarity index 74%
copy from packages/quiver/lib/src/iterables/concat.dart
copy to packages/quiver_iterables/lib/src/count.dart
index b4ab751adb549fe9debce9535a0f780233f14472..093423a08043f53c89514045fe32a1ccee63f360 100644
--- a/packages/quiver/lib/src/iterables/concat.dart
+++ b/packages/quiver_iterables/lib/src/count.dart
@@ -14,9 +14,11 @@
 
 part of quiver.iterables;
 
-/**
- * Returns the concatentation of the input iterables.
- *
- * The returned iterable is a lazily-evaluated view on the input iterables.
- */
-Iterable concat(Iterable<Iterable> iterables) => iterables.expand((x) => x);
+/// Returns an infinite [Iterable] of [num]s, starting from [start] and
+/// increasing by [step].
+Iterable<num> count([num start = 0, num step = 1]) sync* {
+  while (true) {
+    yield start;
+    start += step;
+  }
+}