Add methods to Collection.

sdk/lib/html/html_common/filtered_element_list.dart

Index: sdk/lib/html/html_common/filtered_element_list.dart
diff --git a/sdk/lib/html/html_common/filtered_element_list.dart b/sdk/lib/html/html_common/filtered_element_list.dart
index 5f1f961bac5a61d736ae06440674923b8c189dba..44768c4fcacfe18698896ff9e4e59a48f3d16fcc 100644
--- a/sdk/lib/html/html_common/filtered_element_list.dart
+++ b/sdk/lib/html/html_common/filtered_element_list.dart
@@ -108,6 +108,36 @@ class FilteredElementList implements List {
     return result;
   }
 
+  void remove(Object element) {
+    if (element is! Element) return;
+    for (int i = 0; i < length; i++) {
+      Element indexElement = this[i];
+      if (identical(indexElement, element)) {
+        indexElement.remove();
+        return;
+      }
+    }
+  }
+
+  // Operations defined in terms of [Collections]' [remove].
+
+  void removeAll(Iterable elements) {
+    // This should be optimized to not use [remove] directly.
+    Collections.removeAll(this, elements);
+  }
+
+  void retainAll(Iterable elements) {
+    Collections.retainAll(this, elements);
+  }
+
+  void removeMatching(bool test(Element element)) {
+    Collections.removeMatching(this, test);
+  }
+
+  void retainMatching(bool test(Element element)) {
+    Collections.retainMatching(this, test);
+  }
+
   dynamic reduce(dynamic initialValue,
       dynamic combine(dynamic previousValue, Element element)) {
     return IterableMixinWorkaround.reduce(this, initialValue, combine);
@@ -132,7 +162,6 @@ class FilteredElementList implements List {
     return this[index];
   }
 
-
   bool get isEmpty => _filtered.isEmpty;
   int get length => _filtered.length;
   Element operator [](int index) => _filtered[index];