Fix suspend function with default argument

In JS BE, fix translation of suspend function with default argument
inherited from interface.

See KT-16658

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

@@ -0,0 +1,78 @@
+// IGNORE_BACKEND: NATIVE
+// WITH_RUNTIME
+// WITH_COROUTINES
+import kotlin.coroutines.experimental.*
+import kotlin.coroutines.experimental.intrinsics.*
+
+fun box(): String {
+    async {
+        O.foo()
+        O.foo("second")
+    }
+    while (!finished) {
+        result += "--;"
+        proceed()
+    }
+
+    finished = false
+    asyncSuspend {
+        O.foo()
+        O.foo("second")
+    }
+    while (!finished) {
+        result += "--;"
+        proceed()
+    }
+
+    val expected = "before(first);--;after(first);before(second);--;after(second);--;done;"
+    if (result != expected + expected) return "fail: $result"
+
+    return "OK"
+}
+
+interface I {
+    suspend fun foo(x: String = "first")
+}
+
+object O : I {
+    override suspend fun foo(x: String) {
+        result += "before($x);"
+        sleep()
+        result += "after($x);"
+    }
+}
+
+suspend fun sleep(): Unit = suspendCoroutine { c ->
+    proceed = { c.resume(Unit) }
+}
+
+fun async(f: suspend () -> Unit) {
+    f.startCoroutine(object : Continuation<Unit> {
+        override fun resume(x: Unit) {
+            proceed = {
+                result += "done;"
+                finished = true
+            }
+        }
+        override fun resumeWithException(x: Throwable) {}
+        override val context = EmptyCoroutineContext
+    })
+}
+
+fun asyncSuspend(f: suspend () -> Unit) {
+    val coroutine = f.createCoroutine(object : Continuation<Unit> {
+        override fun resume(x: Unit) {
+            proceed = {
+                result += "done;"
+                finished = true
+            }
+        }
+        override fun resumeWithException(x: Throwable) {}
+        override val context = EmptyCoroutineContext
+    })
+    coroutine.resume(Unit)
+}
+
+var result = ""
+var proceed: () -> Unit = { }
+var finished = false