add generic method comments to a few SDK methods

sdk/lib/collection/iterable.dart

Index: sdk/lib/collection/iterable.dart
diff --git a/sdk/lib/collection/iterable.dart b/sdk/lib/collection/iterable.dart
index e89acc6f1ca91a1a4b5cafe0501da3d5e21c7757..c0d2ee053be9ec890ab9bff660b35a4085176594 100644
--- a/sdk/lib/collection/iterable.dart
+++ b/sdk/lib/collection/iterable.dart
@@ -15,12 +15,13 @@ abstract class IterableMixin<E> implements Iterable<E> {
   // - SetMixin
   // If changing a method here, also change the other copies.
 
-  Iterable map(f(E element)) => new MappedIterable<E, dynamic>(this, f);
+  Iterable/*<T>*/ map/*<T>*/(/*=T*/ f(E element)) =>
+      new MappedIterable<E, dynamic/*=T*/>(this, f);
 
   Iterable<E> where(bool f(E element)) => new WhereIterable<E>(this, f);
 
-  Iterable expand(Iterable f(E element)) =>
-      new ExpandIterable<E, dynamic>(this, f);
+  Iterable/*<T>*/ expand/*<T>*/(Iterable/*<T>*/ f(E element)) =>
+      new ExpandIterable<E, dynamic/*=T*/>(this, f);
 
   bool contains(Object element) {
     for (E e in this) {
@@ -45,8 +46,8 @@ abstract class IterableMixin<E> implements Iterable<E> {
     return value;
   }
 
-  dynamic fold(var initialValue,
-               dynamic combine(var previousValue, E element)) {
+  dynamic/*=T*/ fold/*<T>*/(var/*=T*/ initialValue,
+               dynamic/*=T*/ combine(var/*=T*/ previousValue, E element)) {
     var value = initialValue;
     for (E element in this) value = combine(value, element);
     return value;