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/MostSpecific14.java

@@ -0,0 +1,33 @@
+/*
+ * @test /nodynamiccopyright/
+ * @bug 8034223
+ * @summary Most-specific testing for nested functional interface types
+ * @compile/fail/ref=MostSpecific14.out -XDrawDiagnostics MostSpecific14.java
+ */
+class MostSpecific14 {
+    interface ToNumber { Number get(); }
+    interface ToToNumber { ToNumber get(); }
+    interface Factory<T> { T get(); }
+
+    void m1(Factory<Factory<Object>> f) {}
+    void m1(ToToNumber f) {}
+
+    void m2(Factory<Factory<Number>> f) {}
+    void m2(ToToNumber f) {}
+
+    void m3(Factory<Factory<Integer>> f) {}
+    void m3(ToToNumber f) {}
+
+
+    void test() {
+        m1(() -> () -> 23); // ok: choose ToToNumber
+        m2(() -> () -> 23); // error: ambiguous
+        m3(() -> () -> 23); // ok: choose Factory<Factory<Integer>>
+
+        m1(() -> this::getInteger); // ok: choose ToToNumber
+        m2(() -> this::getInteger); // error: ambiguous
+        m3(() -> this::getInteger); // ok: choose Factory<Factory<Integer>>
+    }
+
+    Integer getInteger() { return 23; }
+}