Always insert the insertion text, even when we can't resolve symbols.

src/EditorFeatures/Test2/IntelliSense/CSharpCompletionCommandHandlerTests.vb

@@ -1839,6 +1839,29 @@ class Program
             End Using
         End Function
 
+        <WpfFact, Trait(Traits.Feature, Traits.Features.Completion)>
+        <WorkItem(12254, "https://github.com/dotnet/roslyn/issues/12254")>
+        Public Async Function TestGenericCallOnTypeContainingAnonymousType() As Task
+            Using state = TestState.CreateCSharpTestState(
+                           <Document><![CDATA[
+using System.Linq;
+
+class Program
+{
+    static void Main(string[] args)
+    {
+        new[] { new { x = 1 } }.ToArr$$
+    }
+}]]></Document>, extraExportedTypes:={GetType(CSharpEditorFormattingService)}.ToList())
+
+                state.SendInvokeCompletionList()
+                state.SendTypeChars("(")
+
+                Await state.WaitForAsynchronousOperationsAsync().ConfigureAwait(True)
+                state.AssertMatchesTextStartingAtLine(7, "new[] { new { x = 1 } }.ToArray(")
+            End Using
+        End Function
+
         <WpfFact, Trait(Traits.Feature, Traits.Features.Completion)>
         Public Async Function TargetTypePreselectionSetterValuey() As Task
             Using state = TestState.CreateCSharpTestState(

src/Features/Core/Portable/Completion/Providers/AbstractSymbolCompletionProvider.cs

@@ -347,7 +347,7 @@ private Task<AbstractSyntaxContext> GetOrCreateContext(Document document, int po
                 }
                 else
                 {
-                    insertionText = selectedItem.DisplayText;
+                    insertionText = SymbolCompletionItem.GetInsertionText(selectedItem);
                 }
             }