Rename {Author,UserAgent}ShadowRoot to {Open,Closed}ShadowRoot.

Source/core/html/HTMLMeterElement.h

Index: Source/core/html/HTMLMeterElement.h
diff --git a/Source/core/html/HTMLMeterElement.h b/Source/core/html/HTMLMeterElement.h
index a671de449abf27af22838c215a5f36c60f316a10..110709b5c2ae0f702aeb269d9e96bae9cdfb1872 100644
--- a/Source/core/html/HTMLMeterElement.h
+++ b/Source/core/html/HTMLMeterElement.h
@@ -69,7 +69,7 @@ private:
     virtual ~HTMLMeterElement();
 
     virtual bool areAuthorShadowsAllowed() const override { return false; }
-    virtual void willAddFirstAuthorShadowRoot() override;
+    virtual void willAddFirstOpenShadowRoot() override;
     RenderMeter* renderMeter() const;
 
     virtual bool supportLabels() const override { return true; }
@@ -78,7 +78,7 @@ private:
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) override;
 
     void didElementStateChange();
-    virtual void didAddUserAgentShadowRoot(ShadowRoot&) override;
+    virtual void didAddClosedShadowRoot(ShadowRoot&) override;
 
     RefPtrWillBeMember<MeterValueElement> m_value;
 };