Recapture shared variables when calling local class constructor

When a local function or class A creates an instance of a local class B
capturing an outer variable 'x', it should use ref for 'x', but not the
value of 'x'.

compiler/testData/codegen/box/localClasses/recaptureVarCapturedInLocalClass1.kt

@@ -0,0 +1,12 @@
+fun box(): String {
+    var x = ""
+
+    class CapturesX {
+        override fun toString() = x
+    }
+
+    fun localFun() = CapturesX()
+
+    x = "OK"
+    return localFun().toString()
+}