Add "lastIndex" length coercion test

test/built-ins/RegExp/prototype/Symbol.replace/coerce-lastindex.js

@@ -0,0 +1,52 @@
+// Copyright (C) 2020 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-regexp.prototype-@@replace
+description: >
+  Length coercion of "lastIndex" property of `this` value.
+info: |
+  RegExp.prototype [ @@replace ] ( string, replaceValue )
+
+  [...]
+  11. Repeat, while done is false
+    a. Let result be ? RegExpExec(rx, S).
+    b. If result is null, set done to true.
+    c. Else,
+      i. Append result to the end of results.
+      ii. If global is false, set done to true.
+      iii. Else,
+        1. Let matchStr be ? ToString(? Get(result, "0")).
+        2. If matchStr is the empty String, then
+          a. Let thisIndex be ? ToLength(? Get(rx, "lastIndex")).
+          b. Let nextIndex be AdvanceStringIndex(S, thisIndex, fullUnicode).
+          c. Perform ? Set(rx, "lastIndex", nextIndex, true).
+features: [Symbol.replace]
+---*/
+
+var r = /./g;
+var execWasCalled = false;
+var coercibleIndex = {
+  valueOf: function() {
+    return Math.pow(2, 54);
+  },
+};
+
+var result = {
+  length: 1,
+  0: '',
+  index: 0,
+};
+
+r.exec = function() {
+  if (execWasCalled) {
+    return null;
+  }
+
+  r.lastIndex = coercibleIndex;
+  execWasCalled = true;
+  return result;
+};
+
+assert.sameValue(r[Symbol.replace]('', ''), '');
+assert.sameValue(r.lastIndex, Math.pow(2, 53));