KT-3503 Can't navigate to implementation of kotlin functions

#KT-3503 Fixed

idea/testData/navigation/implementations/multifile/ImplementFunInJava/ImplementFunInJava.java

@@ -0,0 +1,7 @@
+package testing.jj;
+
+public class JavaBase extends testing.kt.KotlinBase {
+    @Override
+    public void test() {
+    }
+}

idea/testData/navigation/implementations/multifile/ImplementFunInJava/ImplementFunInJava.kt

@@ -0,0 +1,7 @@
+package testing.kt
+
+open class KotlinBase {
+  open fun <caret>test() {}
+}
+
+// REF: (in testing.jj.JavaBase).test()