Add Iterable.range, List.range and int.to.

sdk/lib/core/iterable.dart

Index: sdk/lib/core/iterable.dart
diff --git a/sdk/lib/core/iterable.dart b/sdk/lib/core/iterable.dart
index 6d10da9fa125fbe1b17cc9329c0bcf4544baa6c9..31e11b2e8f95468f5fb899c1825eaa0d95826211 100644
--- a/sdk/lib/core/iterable.dart
+++ b/sdk/lib/core/iterable.dart
@@ -54,6 +54,30 @@ abstract class Iterable<E> {
   }
 
   /**
+   * Create an `Iterable<int>` iterating from `from` to `to`, inclusive.
+   *
+   * The iteration starts with `from` as the first value, and then
+   * progresses towards `to` in increments of `step`, and stops when reaching
+   * or overshooting `to`. If it hits `to` the `to` value is included,

[floitsch, 2014/09/09 09:37:14]

Strongly oppose.
We have a getRange in this class that has different semantics.

+   * otherwise it isn't.
+   *
+   * If `to` is less than `from`, the values are in decreasing order.
+   *
+   * The [step] value must always be positive. It defaults to `1`.
+   */
+  static Iterable<int> range(int from, int to, {int step: 1}) {
+    if (step <= 0) {
+      throw new RangeError.value("Step must be positive, was $step");
+    }
+    final int delta = to - from;
+    if (delta < 0) {
+      step = -step;
+    }
+    final int steps = delta ~/ step + 1;
+    return new Iterable<int>.generate(steps, (n) => from + n * step);
+  }
+
+  /**
    * Returns a new `Iterator` that allows iterating the elements of this
    * `Iterable`.
    */