Drop KFunctionFromReferenceImpl, make FunctionImpl an interface

23 invokes in KFunctionFromReferenceImpl (and consequently, in FunctionImpl)
were needed before 1576160390: a wrapped function
reference must have had the necessary invoke to be called as an instance of a
specific function type. After 1576160390, this is
not needed anymore because KFunctionFromReferenceImpl is now an internal
implementation detail of reflection, and no invoke is ever called on it.

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -7924,6 +7924,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/javaInterop"), Pattern.compile("^(.+)\\.kt$"), true);
         }
 
+        @TestMetadata("lambdaInstanceOf.kt")
+        public void testLambdaInstanceOf() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/javaInterop/lambdaInstanceOf.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("compiler/testData/codegen/box/javaInterop/generics")
         @TestDataPath("$PROJECT_ROOT")
         @RunWith(JUnit3RunnerWithInners.class)