Make document.rootScroller into an origin trial

third_party/WebKit/Source/bindings/core/v8/ConditionalFeatures.cpp

Index: third_party/WebKit/Source/bindings/core/v8/ConditionalFeatures.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/ConditionalFeatures.cpp b/third_party/WebKit/Source/bindings/core/v8/ConditionalFeatures.cpp
index 95e4dc3b13cf4621bb414ec65e615d81ae441c4d..6b28b52df4953a008dc110c22f6ab41c6b32a6e6 100644
--- a/third_party/WebKit/Source/bindings/core/v8/ConditionalFeatures.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/ConditionalFeatures.cpp
@@ -45,6 +45,13 @@ void installConditionalFeaturesCore(const WrapperTypeInfo* wrapperTypeInfo,
       V8Window::installLongTaskObserver(isolate, world, instanceObject,
                                         prototypeObject, interfaceObject);
     }
+  } else if (wrapperTypeInfo == &V8Document::wrapperTypeInfo) {
+    if (RuntimeEnabledFeatures::setRootScrollerEnabled() ||
+        (originTrialContext &&
+         originTrialContext->isTrialEnabled("RootScroller"))) {
+      V8Document::installRootScroller(isolate, world, v8::Local<v8::Object>(),
+                                      prototypeObject, interfaceObject);
+    }
   }
 }