Add more UnwrapNullabilitySymbol calls

src/Features/CSharp/Portable/SignatureHelp/ElementAccessExpressionSignatureHelpProvider.cs

@@ -217,7 +217,7 @@ public override SignatureHelpState GetCurrentArgumentState(SyntaxNode root, int
                     ?? semanticModel.GetSymbolInfo(expression).GetAnySymbol().GetSymbolType();
             }
 
-            indexers = semanticModel.LookupSymbols(position, expressionType, WellKnownMemberNames.Indexer)
+            indexers = semanticModel.LookupSymbols(position, expressionType.UnwrapNullabilitySymbol(), WellKnownMemberNames.Indexer)
                 .OfType<IPropertySymbol>()
                 .ToImmutableArray();
             return true;

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

@@ -139,7 +139,7 @@ private bool ShouldIncludeInTargetTypedCompletionList(ISymbol symbol, ImmutableA
 
             foreach (var inferredType in inferredTypes)
             {
-                if (semanticModel.Compilation.ClassifyCommonConversion(type, inferredType).IsImplicit)
+                if (semanticModel.Compilation.ClassifyCommonConversion(type.UnwrapNullabilitySymbol(), inferredType.UnwrapNullabilitySymbol()).IsImplicit)
                 {
                     return true;
                 }

src/Workspaces/CSharp/Portable/LanguageServices/CSharpTypeInferenceService.TypeInferrer.cs

@@ -1514,7 +1514,7 @@ private IEnumerable<TypeInferenceInfo> GetTypesForRecursivePattern(RecursivePatt
                                 return SpecializedCollections.EmptyEnumerable<TypeInferenceInfo>();
                             }
 
-                            elementTypesBuilder.Add(patternType.InferredType);
+                            elementTypesBuilder.Add(patternType.InferredType.UnwrapNullabilitySymbol());
                         }
 
                         var type = Compilation.CreateTupleTypeSymbol(