Test for kt-524

compiler/testData/checkerWithErrorTypes/quick/regressions/kt524.jet

@@ -0,0 +1,17 @@
+// KT-524 sure() returns T
+// +JDK
+
+namespace StringBuilder
+
+import java.lang.StringBuilder
+
+//import std.io.*
+//import java.io.*
+
+fun main(args : Array<String>) {
+}
+
+val Int.bd : StringBuilder get() = StringBuilder(this.toString())
+fun StringBuilder.plus(other : StringBuilder) : StringBuilder = this.append(other).sure1() // !!!
+
+fun <T : Any> T?.sure1() : T { return if (this != null) this else throw NullPointerException() }