[Test] Properly merge box against java testdata into codegen/box

Previous commit about it was 3199ce03 and it was completely wrong

compiler/testData/codegen/box/sam/propertyReference.kt

@@ -0,0 +1,17 @@
+// DONT_TARGET_EXACT_BACKEND: JS JS_IR JS_IR_ES6 WASM NATIVE
+// MODULE: lib
+// FILE: Base.java
+
+interface Interface {
+    String call(String t);
+}
+
+// MODULE: main(lib)
+// FILE: 1.kt
+
+val String.property: String
+    get() = this
+
+fun box(): String {
+    return Interface(String::property).call("OK")
+}