Delete the Layer Squashing runtime feature.

Source/core/testing/InternalSettings.cpp

Index: Source/core/testing/InternalSettings.cpp
diff --git a/Source/core/testing/InternalSettings.cpp b/Source/core/testing/InternalSettings.cpp
index 4ccfa6df6498facd50389ccea9bf37191a98988a..a674cbf080f868364949d54fc180ce8ff908ed3b 100644
--- a/Source/core/testing/InternalSettings.cpp
+++ b/Source/core/testing/InternalSettings.cpp
@@ -94,7 +94,6 @@ void InternalSettings::Backup::restoreTo(Settings* settings)
     RuntimeEnabledFeatures::setLangAttributeAwareFormControlUIEnabled(m_langAttributeAwareFormControlUIEnabled);
     settings->setImagesEnabled(m_imagesEnabled);
     settings->setDefaultVideoPosterURL(m_defaultVideoPosterURL);
-    settings->setLayerSquashingEnabled(m_originalLayerSquashingEnabled);
     settings->genericFontFamilySettings().reset();
     RuntimeEnabledFeatures::setPseudoClassesInMatchingCriteriaInAuthorShadowTreesEnabled(m_originalPseudoClassesInMatchingCriteriaInAuthorShadowTreesEnabled);
     RuntimeEnabledFeatures::setImageColorProfilesEnabled(m_originalImageColorProfilesEnabled);
@@ -215,14 +214,6 @@ void InternalSettings::setViewportEnabled(bool enabled, ExceptionState& exceptio
     settings()->setViewportEnabled(enabled);
 }
 
-// FIXME: This is a temporary flag and should be removed once squashing is
-// ready (crbug.com/261605).
-void InternalSettings::setLayerSquashingEnabled(bool enabled, ExceptionState& exceptionState)
-{
-    InternalSettingsGuardForSettings();
-    settings()->setLayerSquashingEnabled(enabled);
-}
-
 void InternalSettings::setStandardFontFamily(const AtomicString& family, const String& script, ExceptionState& exceptionState)
 {
     InternalSettingsGuardForSettings();