Fix bugs in GrowableList.remove*.

sdk/lib/core/collection.dart

Index: sdk/lib/core/collection.dart
diff --git a/sdk/lib/core/collection.dart b/sdk/lib/core/collection.dart
index 48ab1de2e88cd30f0c8d0e212d2077d6c472a622..f0274fdf16da87ad62379f2fad66695e848179aa 100644
--- a/sdk/lib/core/collection.dart
+++ b/sdk/lib/core/collection.dart
@@ -84,4 +84,11 @@ abstract class Collection<E> extends Iterable<E> {
   void retainMatching(bool test(E element)) {
     IterableMixinWorkaround.retainMatching(this, test);
   }
+
+  /**
+   * Removes all elements of this collection.
+   */
+  void clear() {
+    IterableMixinWorkaround.removeMatching((E e) => true);
+  }
 }