Closure conversion: simple tests work.

compiler/testData/ir/box/closureConversion1.kt

@@ -0,0 +1,6 @@
+fun foo(x: String): String {
+    fun bar(y: String) = x + y
+    return bar("K")
+}
+
+fun box() = foo("O")

compiler/testData/ir/box/closureConversion2.kt

@@ -0,0 +1,8 @@
+fun <X : Any> foo(x: X): String {
+    fun <Y : Any> bar(y: Y) =
+            x.toString() + y.toString()
+
+    return bar("K")
+}
+
+fun box() = foo("O")

compiler/testData/ir/box/closureConversion3.kt

@@ -0,0 +1,11 @@
+fun foo(x: String): String {
+    fun bar(y: String): String {
+        fun qux(z: String): String =
+                x + y + z
+        return qux("")
+    }
+    return bar("K")
+}
+
+fun box(): String =
+        foo("O")