Convert FunctionBase to Kotlin, add type parameter to Lambda

This will make it possible to avoid raw types when inheriting from both
FunctionBase and Function<R>. This change adds a generic type parameter
to FunctionBase and Lambda which is not source-breaking under our policy
because both FunctionBase and Lambda are internal classes (located in
package kotlin.jvm.internal)

libraries/stdlib/jvm/runtime/kotlin/jvm/internal/FunctionBase.kt

@@ -3,10 +3,8 @@
  * that can be found in the license/LICENSE.txt file.
  */
 
-package kotlin.jvm.internal;
+package kotlin.jvm.internal
 
-import kotlin.Function;
-
-public interface FunctionBase extends Function {
-    int getArity();
+interface FunctionBase<out R> : Function<R> {
+    val arity: Int
 }

libraries/stdlib/jvm/runtime/kotlin/jvm/internal/Lambda.kt

@@ -7,8 +7,6 @@ package kotlin.jvm.internal
 
 import java.io.Serializable
 
-abstract class Lambda(private val arity: Int) : FunctionBase, Serializable {
-    override fun getArity(): Int = arity
-
+abstract class Lambda<out R>(override val arity: Int) : FunctionBase<R>, Serializable {
     override fun toString(): String = Reflection.renderLambdaToString(this)
 }