Add position: sticky as supported position value when CSSStickyPosition is enabled.

Source/core/testing/InternalSettings.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 Apple 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 41 matching lines @@
     if (!page()) { \
         exceptionState.throwDOMException(InvalidAccessError, "The page object cannot be obtained."); \
         return; \
     }
 
 namespace blink {
 
 InternalSettings::Backup::Backup(Settings* settings)
     : m_originalAuthorShadowDOMForAnyElementEnabled(RuntimeEnabledFeatures::authorShadowDOMForAnyElementEnabled())
     , m_originalCSP(RuntimeEnabledFeatures::experimentalContentSecurityPolicyFeaturesEnabled())
+    , m_originalCSSStickyPositionEnabled(RuntimeEnabledFeatures::cssStickyPositionEnabled())
     , m_originalOverlayScrollbarsEnabled(RuntimeEnabledFeatures::overlayScrollbarsEnabled())
     , m_originalEditingBehavior(settings->editingBehaviorType())
     , m_originalTextAutosizingEnabled(settings->textAutosizingEnabled())
     , m_originalTextAutosizingWindowSizeOverride(settings->textAutosizingWindowSizeOverride())
     , m_originalAccessibilityFontScaleFactor(settings->accessibilityFontScaleFactor())
     , m_originalMediaTypeOverride(settings->mediaTypeOverride())
     , m_originalDisplayModeOverride(settings->displayModeOverride())
     , m_originalMockScrollbarsEnabled(settings->mockScrollbarsEnabled())
     , m_originalMockGestureTapHighlightsEnabled(settings->mockGestureTapHighlightsEnabled())
     , m_langAttributeAwareFormControlUIEnabled(RuntimeEnabledFeatures::langAttributeAwareFormControlUIEnabled())
     , m_imagesEnabled(settings->imagesEnabled())
     , m_defaultVideoPosterURL(settings->defaultVideoPosterURL())
     , m_originalLayerSquashingEnabled(settings->layerSquashingEnabled())
     , m_originalImageColorProfilesEnabled(RuntimeEnabledFeatures::imageColorProfilesEnabled())
     , m_originalImageAnimationPolicy(settings->imageAnimationPolicy())
     , m_originalScrollTopLeftInteropEnabled(RuntimeEnabledFeatures::scrollTopLeftInteropEnabled())
 {
 }
 
 void InternalSettings::Backup::restoreTo(Settings* settings)
 {
     RuntimeEnabledFeatures::setAuthorShadowDOMForAnyElementEnabled(m_originalAuthorShadowDOMForAnyElementEnabled);
     RuntimeEnabledFeatures::setExperimentalContentSecurityPolicyFeaturesEnabled(m_originalCSP);
+    RuntimeEnabledFeatures::setCSSStickyPositionEnabled(m_originalCSSStickyPositionEnabled);
     RuntimeEnabledFeatures::setOverlayScrollbarsEnabled(m_originalOverlayScrollbarsEnabled);
     settings->setEditingBehaviorType(m_originalEditingBehavior);
     settings->setTextAutosizingEnabled(m_originalTextAutosizingEnabled);
     settings->setTextAutosizingWindowSizeOverride(m_originalTextAutosizingWindowSizeOverride);
     settings->setAccessibilityFontScaleFactor(m_originalAccessibilityFontScaleFactor);
     settings->setMediaTypeOverride(m_originalMediaTypeOverride);
     settings->setDisplayModeOverride(m_originalDisplayModeOverride);
     settings->setMockScrollbarsEnabled(m_originalMockScrollbarsEnabled);
     settings->setMockGestureTapHighlightsEnabled(m_originalMockGestureTapHighlightsEnabled);
     RuntimeEnabledFeatures::setLangAttributeAwareFormControlUIEnabled(m_langAttributeAwareFormControlUIEnabled);
@@ skipping 80 matching lines @@
 {
     InternalSettingsGuardForSettings();
     settings()->setMockGestureTapHighlightsEnabled(enabled);
 }
 
 void InternalSettings::setAuthorShadowDOMForAnyElementEnabled(bool isEnabled)
 {
     RuntimeEnabledFeatures::setAuthorShadowDOMForAnyElementEnabled(isEnabled);
 }
 
+void InternalSettings::setCSSStickyPositionEnabled(bool enabled)
+{
+    RuntimeEnabledFeatures::setCSSStickyPositionEnabled(enabled);
+}
+
 void InternalSettings::setExperimentalContentSecurityPolicyFeaturesEnabled(bool enabled)
 {
     RuntimeEnabledFeatures::setExperimentalContentSecurityPolicyFeaturesEnabled(enabled);
 }
 
 void InternalSettings::setImageColorProfilesEnabled(bool enabled)
 {
     RuntimeEnabledFeatures::setImageColorProfilesEnabled(enabled);
 }
 
@@ skipping 303 matching lines @@
     settings()->setLogDnsPrefetchAndPreconnect(enabled);
 }
 
 void InternalSettings::setPreloadLogging(bool enabled, ExceptionState& exceptionState)
 {
     InternalSettingsGuardForSettings();
     settings()->setLogPreload(enabled);
 }
 
 }