Don't update analyzed nullability for parameter conversions (#36881)

* Don't update analyzed nullability for param conversions
* Fix test types

Author: chsienki

src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs

@@ -204,9 +204,9 @@ private TypeWithState ResultType
             get => _visitResult.RValueType;
         }
 
-        private void SetResultType(BoundExpression expression, TypeWithState type)
+        private void SetResultType(BoundExpression expression, TypeWithState type, bool updateAnalyzedNullability = true)
         {
-            SetResult(expression, resultType: type, lvalueType: type.ToTypeWithAnnotations());
+            SetResult(expression, resultType: type, lvalueType: type.ToTypeWithAnnotations(), updateAnalyzedNullability: updateAnalyzedNullability);
         }
 
         /// <summary>
@@ -3188,7 +3188,7 @@ private void VisitArgumentConversionAndInboundAssignmentsAndPreConditions(
 
                         // If the parameter has annotations, we perform an additional check for nullable value types
                         CheckDisallowedNullAssignment(stateAfterConversion, parameterAnnotations, argumentNoConversion.Syntax.Location);
-                        SetResultType(argumentNoConversion, stateAfterConversion);
+                        SetResultType(argumentNoConversion, stateAfterConversion, updateAnalyzedNullability: false);
                     }
                     break;
                 case RefKind.Ref:

src/Compilers/CSharp/Test/Semantic/Semantics/NullableReferenceTypesTests.cs

@@ -34457,9 +34457,9 @@ static void F7(IOut<object>? x7, IOut<object> y7)
         }
 
         [Fact]
+        [WorkItem(35012, "https://github.com/dotnet/roslyn/issues/35012")]
         public void IdentityConversion_NullCoalescingOperator_02()
         {
-            // F1's types are incorrect. See https://github.com/dotnet/roslyn/issues/35012
             var source =
 @"interface IIn<in T> { }
 interface IOut<out T> { }
@@ -34482,8 +34482,8 @@ static T FOut<T>(IOut<T>? x)
     }
     static void F1(IIn<object>? x1, IIn<object?>? y1)
     {
-        FIn((x1 ?? y1)/*T:IIn<object?>?*/);
-        FIn((y1 ?? x1)/*T:IIn<object?>?*/);
+        FIn((x1 ?? y1)/*T:IIn<object!>?*/);
+        FIn((y1 ?? x1)/*T:IIn<object!>?*/);
     }
     static void F2(IOut<object>? x2, IOut<object?>? y2)
     {
@@ -34494,10 +34494,10 @@ static void F3(object? x3, object? y3)
     {
         FIn((FIn(x3) ?? FIn(y3))/*T:IIn<object?>?*/); // A
         if (x3 == null) return;
-        FIn((FIn(x3) ?? FIn(y3))/*T:IIn<object?>?*/); // B
-        FIn((FIn(y3) ?? FIn(x3))/*T:IIn<object?>?*/); // C
+        FIn((FIn(x3) ?? FIn(y3))/*T:IIn<object!>?*/); // B
+        FIn((FIn(y3) ?? FIn(x3))/*T:IIn<object!>?*/); // C
         if (y3 == null) return;
-        FIn((FIn(x3) ?? FIn(y3))/*T:IIn<object?>?*/); // D
+        FIn((FIn(x3) ?? FIn(y3))/*T:IIn<object!>?*/); // D
     }
     static void F4(object? x4, object? y4)
     {