8034223: Most-specific should not have any special treatment for boxed vs. unboxed types

Rewrite most-specific logic to conform to JLS 8 15.12.2.5

Reviewed-by: vromero

langtools/test/tools/javac/lambda/MostSpecific13.java

@@ -0,0 +1,21 @@
+/*
+ * @test /nodynamiccopyright/
+ * @bug 8034223
+ * @summary Most-specific testing with inference variables in function parameter types
+ * @compile/fail/ref=MostSpecific13.out -XDrawDiagnostics MostSpecific13.java
+ */
+class MostSpecific13 {
+
+    interface UnaryOp<T> { T apply(T arg); }
+    interface IntegerToNumber { Number apply(Integer arg); }
+
+    <T> void m(UnaryOp<T> f) {}
+    void m(IntegerToNumber f) {}
+
+    void test() {
+        m((Integer i) -> i); // error
+        m(this::id); // error
+    }
+
+    Integer id(Integer arg) { return arg; }
+}