Introduce FunctionImpl and ExtensionFunctionImpl classes

Old FunctionImpl0,1,2,... will be dropped since they had no purpose

core/runtime.jvm/src/kotlin/jvm/internal/ExtensionFunctionImpl.kt

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kotlin.jvm.internal
+
+import java.io.Serializable
+
+public abstract class ExtensionFunctionImpl<in T, out R> : Serializable {
+    override fun toString() = "${getClass().getGenericInterfaces()[0]}"
+}

core/runtime.jvm/src/kotlin/jvm/internal/FunctionImpl.kt

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kotlin.jvm.internal
+
+import java.io.Serializable
+
+public abstract class FunctionImpl<out R> : Serializable {
+    override fun toString() = "${getClass().getGenericInterfaces()[0]}"
+}