Debugger, BE: Provide Java-like stepping for 'for' loops

- Visit '}' instead of 'for' keyword on post-condition
- Visit 'for' keyword on pre-condition

compiler/testData/debug/localVariables/destructuringInFor.kt

@@ -16,5 +16,4 @@ fun box() {
 // TestKt:7: map:java.util.Collections$SingletonMap
 // TestKt:9: map:java.util.Collections$SingletonMap, a:java.lang.String, b:java.lang.String
 // TestKt:7: map:java.util.Collections$SingletonMap
-// TestKt:8: map:java.util.Collections$SingletonMap
 // TestKt:11: map:java.util.Collections$SingletonMap

compiler/testData/debug/stepping/for.kt

@@ -0,0 +1,21 @@
+//FILE: test.kt
+fun box() {
+    for (i in 1..3) {
+        foo(i)
+    }
+}
+
+inline fun foo(n: Int) {}
+
+// LINENUMBERS
+// TestKt.box():3
+// TestKt.box():4
+// TestKt.box():8
+// TestKt.box():3
+// TestKt.box():4
+// TestKt.box():8
+// TestKt.box():3
+// TestKt.box():4
+// TestKt.box():8
+// TestKt.box():3
+// TestKt.box():6