[FE 1.0] Process builder inference stub types with different nullability properly

^KT-49887 Fixed

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/JsCodegenBoxTestGenerated.java

@@ -14608,6 +14608,12 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
                 runTest("compiler/testData/codegen/box/inference/builderInference/kt49285.kt");
             }
 
+            @Test
+            @TestMetadata("kt49887.kt")
+            public void testKt49887() throws Exception {
+                runTest("compiler/testData/codegen/box/inference/builderInference/kt49887.kt");
+            }
+
             @Test
             @TestMetadata("labaledCall.kt")
             public void testLabaledCall() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/IrJsCodegenBoxTestGenerated.java

@@ -14572,6 +14572,12 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
                 runTest("compiler/testData/codegen/box/inference/builderInference/kt49285.kt");
             }
 
+            @Test
+            @TestMetadata("kt49887.kt")
+            public void testKt49887() throws Exception {
+                runTest("compiler/testData/codegen/box/inference/builderInference/kt49887.kt");
+            }
+
             @Test
             @TestMetadata("labaledCall.kt")
             public void testLabaledCall() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/testOld/wasm/semantics/IrCodegenBoxWasmTestGenerated.java

@@ -12265,6 +12265,11 @@ public class IrCodegenBoxWasmTestGenerated extends AbstractIrCodegenBoxWasmTest
                 runTest("compiler/testData/codegen/box/inference/builderInference/kt48445.kt");
             }
 
+            @TestMetadata("kt49887.kt")
+            public void testKt49887() throws Exception {
+                runTest("compiler/testData/codegen/box/inference/builderInference/kt49887.kt");
+            }
+
             @TestMetadata("labaledCall.kt")
             public void testLabaledCall() throws Exception {
                 runTest("compiler/testData/codegen/box/inference/builderInference/labaledCall.kt");