Add methods to Collection.

tools/dom/templates/immutable_list_mixin.darttemplate

   // -- start List<$E> mixins.
   // $E is the element type.
 
   // From Iterable<$E>:
 
   Iterator<$E> get iterator {
     // Note: NodeLists are not fixed size. And most probably length shouldn't
     // be cached in both iterator _and_ forEach method. For now caching it
     // for consistency.
     return new FixedSizeListIterator<$E>(this);
@@ skipping 77 matching lines @@
   void set length(int value) {
     throw new UnsupportedError("Cannot resize immutable List.");
   }
 $endif
 
 $if DEFINE_CLEAR
   void clear() {
     throw new UnsupportedError("Cannot clear immutable List.");
   }
 $else
-  // contains() defined by IDL.
+  // clear() defined by IDL.
 $endif
 
   void sort([int compare($E a, $E b)]) {
     throw new UnsupportedError("Cannot sort immutable List.");
   }
 
   int indexOf($E element, [int start = 0]) =>
       Lists.indexOf(this, element, start, this.length);
 
   int lastIndexOf($E element, [int start]) {
@@ skipping 15 matching lines @@
     if (length == 1) return this[0];
     if (length == 0) throw new StateError("No elements");
     throw new StateError("More than one element");
   }
 
   $E min([int compare($E a, $E b)]) => Collections.min(this, compare);
 
   $E max([int compare($E a, $E b)]) => Collections.max(this, compare);
 
   $E removeAt(int pos) {
-    throw new UnsupportedError("Cannot removeAt on immutable List.");
+    throw new UnsupportedError("Cannot remove from immutable List.");
   }
 
   $E removeLast() {
-    throw new UnsupportedError("Cannot removeLast on immutable List.");
+    throw new UnsupportedError("Cannot remove from immutable List.");
+  }
+
+  void remove(Object object) {
+    throw new UnsupportedError("Cannot remove from immutable List.");
+  }
+
+  void removeAll(Iterable elements) {
+    throw new UnsupportedError("Cannot remove from immutable List.");
+  }
+
+  void retainAll(Iterable elements) {
+    throw new UnsupportedError("Cannot remove from immutable List.");
+  }
+
+  void removeMatching(bool test($E element)) {
+    throw new UnsupportedError("Cannot remove from immutable List.");
+  }
+
+  void retainMatching(bool test($E element)) {
+    throw new UnsupportedError("Cannot remove from immutable List.");
   }
 
   void setRange(int start, int rangeLength, List<$E> from, [int startFrom]) {
     throw new UnsupportedError("Cannot setRange on immutable List.");
   }
 
   void removeRange(int start, int rangeLength) {
     throw new UnsupportedError("Cannot removeRange on immutable List.");
   }
 
   void insertRange(int start, int rangeLength, [$E initialValue]) {
     throw new UnsupportedError("Cannot insertRange on immutable List.");
   }
 
   List<$E> getRange(int start, int rangeLength) =>
       Lists.getRange(this, start, rangeLength, <$E>[]);
 
   // -- end List<$E> mixins.