Have bindings layer assume and insist that all interface types are GCed.

third_party/WebKit/Source/core/editing/Selection.idl

 /*
  * Copyright (C) 2007 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Google Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 14 matching lines @@
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 // http://w3c.github.io/selection-api/#idl-def-Selection
 
 // TODO(yoichio): All long types should be unsigned long. crbug.com/391673
 [
     ImplementedAs=DOMSelection,
-    GarbageCollected,
 ] interface Selection {
     [MeasureAs=SelectionAnchorNode] readonly attribute Node? anchorNode;
     [MeasureAs=SelectionAnchorOffset] readonly attribute long anchorOffset;
     [MeasureAs=SelectionFocusNode] readonly attribute Node? focusNode;
     [MeasureAs=SelectionFocusOffset] readonly attribute long focusOffset;
     [MeasureAs=SelectionIsCollapsed] readonly attribute boolean isCollapsed;
     [MeasureAs=SelectionRangeCount] readonly attribute long rangeCount;
     [MeasureAs=SelectionType] readonly attribute DOMString type;
     [MeasureAs=SelectionGetRangeAt, RaisesException] Range getRangeAt(long index);
     [MeasureAs=SelectionAddRange] void addRange(Range range);
@@ skipping 27 matching lines @@
     [MeasureAs=SelectionBaseNode] readonly attribute Node? baseNode;
     [MeasureAs=SelectionBaseOffset] readonly attribute long baseOffset;
     [MeasureAs=SelectionExtentNode] readonly attribute Node? extentNode;
     [MeasureAs=SelectionExtentOffset] readonly attribute long extentOffset;
 
     // https://github.com/w3c/selection-api/issues/37
     [MeasureAs=SelectionModify] void modify([Default=Undefined] optional DOMString alter,
                                             [Default=Undefined] optional DOMString direction,
                                             [Default=Undefined] optional DOMString granularity);
 };