[FIR-TEST] Add new testdata generated after changes in previous commit

compiler/testData/diagnostics/testsWithStdLib/elvisOnJavaList.fir.kt

@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+
+// FILE: P.java
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class P {
+    public List<Integer> getList() {
+        return new ArrayList<Integer>();
+    }
+}
+
+// FILE: Test.kt
+
+fun foo(c: P): MutableList<Int> {
+    // Error should be here: see KT-8168 Typechecker fails for platform collection type
+    return c.getList() ?: listOf()
+}