Make createCoroutine return a safe continuation

#KT-15718 Fixed

compiler/testData/codegen/box/coroutines/createCoroutineSafe.kt

@@ -0,0 +1,25 @@
+// WITH_RUNTIME
+// WITH_COROUTINES
+import kotlin.coroutines.experimental.*
+import kotlin.coroutines.experimental.intrinsics.*
+
+fun builder(c: suspend () -> Unit) {
+    val x = c.createCoroutine(EmptyContinuation)
+
+    x.resume(Unit)
+    x.resume(Unit)
+}
+
+fun box(): String {
+    var result = ""
+
+    try {
+        builder {
+            result = "OK"
+        }
+    } catch (e: IllegalStateException) {
+        return result
+    }
+
+    return "fail: $result"
+}

compiler/testData/codegen/box/coroutines/illegalState.kt

@@ -15,9 +15,14 @@ fun builder1(c: suspend () -> Unit) {
 
 fun builder2(c: suspend () -> Unit) {
     val continuation = c.createCoroutine(EmptyContinuation)
-    val declaredField = continuation.javaClass.superclass.getDeclaredField("label")
+
+    val delegateField = continuation.javaClass.getDeclaredField("delegate")
+    delegateField.setAccessible(true)
+    val originalContinuation = delegateField.get(continuation)
+
+    val declaredField = originalContinuation.javaClass.superclass.getDeclaredField("label")
     declaredField.setAccessible(true)
-    declaredField.set(continuation, -3)
+    declaredField.set(originalContinuation, -3)
     continuation.resume(Unit)
 }