Rename unsubscribe to cancel.

sdk/lib/async/merge_stream.dart

Index: sdk/lib/async/merge_stream.dart
diff --git a/sdk/lib/async/merge_stream.dart b/sdk/lib/async/merge_stream.dart
index fcc9abac0e49569e55422aa3de40429aef9bf842..2a9d273e2cd76dfac4312efc91e4581bf38dd841 100644
--- a/sdk/lib/async/merge_stream.dart
+++ b/sdk/lib/async/merge_stream.dart
@@ -40,7 +40,7 @@ class _SupercedeEntry<T> {
 
   void stop() {
     if (!isDone) {
-      subscription.unsubscribe();
+      subscription.cancel();
       subscription = null;
     }
   }
@@ -164,10 +164,10 @@ class _CycleEntry<T> {
 
   _CycleEntry(this.stream, this.source);
 
-  void unsubscribe() {
+  void cancel() {
     // This method may be called event if this entry has never been activated.
     if (subscription != null) {
-      subscription.unsubscribe();
+      subscription.cancel();
       subscription = null;
     }
   }
@@ -242,7 +242,7 @@ class CyclicScheduleStream<T> extends _MultiStreamImpl<T> {
       return;
     }
     for (_CycleEntry entry = _currentEntry; entry != null; entry = entry.next) {
-      entry.unsubscribe();
+      entry.cancel();
     }
   }