Recommit changing List.skip/take/revert returns Iterable and remove mappedBy.

tests/corelib/iterable_take_test.dart

Index: tests/corelib/iterable_take_test.dart
diff --git a/tests/corelib/iterable_take_test.dart b/tests/corelib/iterable_take_test.dart
index c775c52c57a4c41ec2e12eb50b5ed02867d016bb..3910769846fff1d9ad5ed2867140f831052db680 100644
--- a/tests/corelib/iterable_take_test.dart
+++ b/tests/corelib/iterable_take_test.dart
@@ -13,16 +13,12 @@ main() {
   Set set2 = new Set();
 
   Iterable<int> take0 = list1.take(0);
-  Expect.isTrue(take0 is List);
-  Expect.isTrue(take0.take(2).take(1) is List);
   Iterator<int> it = take0.iterator;
   Expect.isNull(it.current);
   Expect.isFalse(it.moveNext());
   Expect.isNull(it.current);
 
   Iterable<int> take1 = list1.take(1);
-  Expect.isTrue(take1 is List);
-  Expect.isTrue(take1.take(2).take(1) is List);
   it = take1.iterator;
   Expect.isNull(it.current);
   Expect.isTrue(it.moveNext());
@@ -32,8 +28,6 @@ main() {
 
   Iterable<int> take2 = list1.take(2);
   it = take2.iterator;
-  Expect.isTrue(take2 is List);
-  Expect.isTrue(take2.take(2).take(1) is List);
   Expect.isNull(it.current);
   Expect.isTrue(it.moveNext());
   Expect.equals(1, it.current);
@@ -43,8 +37,6 @@ main() {
   Expect.isNull(it.current);
 
   Iterable<int> take3 = list1.take(3);
-  Expect.isTrue(take3 is List);
-  Expect.isTrue(take3.take(2).take(1) is List);
   it = take3.iterator;
   Expect.isNull(it.current);
   Expect.isTrue(it.moveNext());
@@ -57,8 +49,6 @@ main() {
   Expect.isNull(it.current);
 
   Iterable<int> take4 = list1.take(4);
-  Expect.isTrue(take4 is List);
-  Expect.isTrue(take4.take(2).take(1) is List);
   it = take4.iterator;
   Expect.isNull(it.current);
   Expect.isTrue(it.moveNext());
@@ -115,16 +105,12 @@ main() {
   Expect.isNull(it.current);
 
   take0 = list2.take(0);
-  Expect.isTrue(take0 is List);
-  Expect.isTrue(take0.take(2).take(1) is List);
   it = take0.iterator;
   Expect.isNull(it.current);
   Expect.isFalse(it.moveNext());
   Expect.isNull(it.current);
 
   take1 = list2.take(1);
-  Expect.isTrue(take1 is List);
-  Expect.isTrue(take1.take(2).take(1) is List);
   it = take1.iterator;
   Expect.isNull(it.current);
   Expect.isTrue(it.moveNext());
@@ -133,8 +119,6 @@ main() {
   Expect.isNull(it.current);
 
   take2 = list2.take(2);
-  Expect.isTrue(take2 is List);
-  Expect.isTrue(take2.take(2).take(1) is List);
   it = take2.iterator;
   Expect.isNull(it.current);
   Expect.isTrue(it.moveNext());
@@ -145,8 +129,6 @@ main() {
   Expect.isNull(it.current);
 
   take3 = list2.take(3);
-  Expect.isTrue(take3 is List);
-  Expect.isTrue(take3.take(2).take(1) is List);
   it = take3.iterator;
   Expect.isNull(it.current);
   Expect.isTrue(it.moveNext());
@@ -157,16 +139,12 @@ main() {
   Expect.isNull(it.current);
 
   Iterable<String> take02 = list3.take(0);
-  Expect.isTrue(take02 is List);
-  Expect.isTrue(take02.take(2).take(1) is List);
   Iterator<String> it2 = take02.iterator;
   Expect.isNull(it2.current);
   Expect.isFalse(it2.moveNext());
   Expect.isNull(it2.current);
 
   Iterable<String> take12 = list3.take(1);
-  Expect.isTrue(take12 is List);
-  Expect.isTrue(take12.take(2).take(1) is List);
   it2 = take12.iterator;
   Expect.isNull(it2.current);
   Expect.isFalse(it2.moveNext());