Fixed inference in a simple case.

Try number lower bounds before upper bounds when computing a value.

compiler/testData/diagnostics/tests/inference/tryNumberLowerBoundsBeforeUpperBounds.kt

@@ -0,0 +1,6 @@
+public inline fun <T: Any> iterate(initialValue: T, nextFunction: (T) -> T?): Iterator<T> =
+        throw Exception("$initialValue $nextFunction")
+
+fun foo() {
+    iterate(3) { n -> if (n > 0) n - 1 else null }
+}