Use patterns in more places.

src/Features/CSharp/Portable/Completion/CompletionProviders/XmlDocCommentCompletionProvider.cs

@@ -168,14 +168,14 @@ private void RemoveExistingTags(DocumentationCommentTriviaSyntax parentTrivia, I
 
         private IEnumerable<CompletionItem> GetTagsForSymbol(ISymbol symbol, DocumentationCommentTriviaSyntax trivia)
         {
-            if (symbol is IMethodSymbol)
+            if (symbol is IMethodSymbol method)
             {
-                return GetTagsForMethod((IMethodSymbol)symbol, trivia);
+                return GetTagsForMethod(method, trivia);
             }
 
-            if (symbol is IPropertySymbol)
+            if (symbol is IPropertySymbol property)
             {
-                return GetTagsForProperty((IPropertySymbol)symbol, trivia);
+                return GetTagsForProperty(property, trivia);
             }
 
             if (symbol is INamedTypeSymbol namedType)