Add `if` statement test

test/annexB/language/statements/if/emulated-undefined.js

@@ -0,0 +1,31 @@
+// Copyright (C) 2020 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-if-statement-runtime-semantics-evaluation
+description: >
+  ToBoolean returns `false` for [[IsHTMLDDA]] object; first Statement is not evaluated.
+info: |
+  IfStatement : if ( Expression ) Statement else Statement
+
+  1. Let exprRef be the result of evaluating Expression.
+  2. Let exprValue be ! ToBoolean(? GetValue(exprRef)).
+  3. If exprValue is true, then
+    [...]
+  4. Else,
+    a. Let stmtCompletion be the result of evaluating the second Statement.
+
+  The [[IsHTMLDDA]] Internal Slot / Changes to ToBoolean
+
+  1. If argument has an [[IsHTMLDDA]] internal slot, return false.
+  2. Return true.
+features: [IsHTMLDDA]
+---*/
+
+var result = false;
+if ($262.IsHTMLDDA) {
+  throw new Test262Error("unreachable");
+} else {
+  result = true;
+}
+
+assert(result);