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

third_party/WebKit/Source/core/testing/InternalSettings.idl

 /*
  * Copyright (C) 2012 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.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
  *     documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * 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.
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 [
-    GarbageCollected,
 ] interface InternalSettings : InternalSettingsGenerated {
     // All methods which access Page::settings() can raise an exception
     // when the page cannot be accessed. (Such as during page tear-down.)
     [RaisesException] void setMockScrollbarsEnabled(boolean enabled);
     [RaisesException] void setMockGestureTapHighlightsEnabled(boolean enabled);
     [RaisesException] void setStandardFontFamily(DOMString family, DOMString script);
     [RaisesException] void setSerifFontFamily(DOMString family, DOMString script);
     [RaisesException] void setSansSerifFontFamily(DOMString family, DOMString script);
     [RaisesException] void setFixedFontFamily(DOMString family, DOMString script);
     [RaisesException] void setCursiveFontFamily(DOMString family, DOMString script);
@@ skipping 21 matching lines @@
     // cannot be changed after process start.  These setters should
     // be removed or moved onto internals.runtimeFlags:
     void setCSSStickyPositionEnabled(boolean enabled);
     void setLangAttributeAwareFormControlUIEnabled(boolean enabled);
     void setOverlayScrollbarsEnabled(boolean enabled);
     void setExperimentalContentSecurityPolicyFeaturesEnabled(boolean enabled);
     void setImageColorProfilesEnabled(boolean enabled);
     void setScrollTopLeftInteropEnabled(boolean enabled);
     void setLinkHeaderEnabled(boolean enabled);
 };