Add tests for ToPropertyKey called once in **= and logical assignment

test/language/expressions/compound-assignment/left-hand-side-property-reference-topropertykey-once-add.js

@@ -0,0 +1,46 @@
+// Copyright (C) 2026 Sergey Rubanov. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-assignment-operators-runtime-semantics-evaluation
+description: >
+  ToPropertyKey is called only once on the key of base[prop] += value.
+info: |
+  AssignmentExpression : LeftHandSideExpression AssignmentOperator AssignmentExpression
+
+  1. Let leftRef be ? Evaluation of LeftHandSideExpression.
+  ...
+  3. Let leftValue be ? GetValue(leftRef).
+  ...
+  9. Perform ? PutValue(leftRef, result).
+
+  GetValue ( refRecord )
+
+  ...
+  3. If IsPropertyReference(refRecord) is true, then
+    ...
+    c. If refRecord.[[ReferencedName]] is not a property key, then
+      i. Set refRecord.[[ReferencedName]] to ? ToPropertyKey(refRecord.[[ReferencedName]]).
+
+  PutValue ( refRecord, value )
+
+  ...
+  3. If IsPropertyReference(refRecord) is true, then
+    ...
+    c. If refRecord.[[ReferencedName]] is not a property key, then
+      i. Set refRecord.[[ReferencedName]] to ? ToPropertyKey(refRecord.[[ReferencedName]]).
+---*/
+
+var count = 0;
+var prop = {
+  toString: function() {
+    count++;
+    return "p";
+  }
+};
+var base = { p: 2 };
+
+base[prop] += 3;
+
+assert.sameValue(count, 1, "ToPropertyKey(prop) is performed once");
+assert.sameValue(base.p, 5, "the result is assigned to the converted key");

test/language/expressions/compound-assignment/left-hand-side-property-reference-topropertykey-once-bitand.js

@@ -0,0 +1,46 @@
+// Copyright (C) 2026 Sergey Rubanov. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-assignment-operators-runtime-semantics-evaluation
+description: >
+  ToPropertyKey is called only once on the key of base[prop] &= value.
+info: |
+  AssignmentExpression : LeftHandSideExpression AssignmentOperator AssignmentExpression
+
+  1. Let leftRef be ? Evaluation of LeftHandSideExpression.
+  ...
+  3. Let leftValue be ? GetValue(leftRef).
+  ...
+  9. Perform ? PutValue(leftRef, result).
+
+  GetValue ( refRecord )
+
+  ...
+  3. If IsPropertyReference(refRecord) is true, then
+    ...
+    c. If refRecord.[[ReferencedName]] is not a property key, then
+      i. Set refRecord.[[ReferencedName]] to ? ToPropertyKey(refRecord.[[ReferencedName]]).
+
+  PutValue ( refRecord, value )
+
+  ...
+  3. If IsPropertyReference(refRecord) is true, then
+    ...
+    c. If refRecord.[[ReferencedName]] is not a property key, then
+      i. Set refRecord.[[ReferencedName]] to ? ToPropertyKey(refRecord.[[ReferencedName]]).
+---*/
+
+var count = 0;
+var prop = {
+  toString: function() {
+    count++;
+    return "p";
+  }
+};
+var base = { p: 6 };
+
+base[prop] &= 3;
+
+assert.sameValue(count, 1, "ToPropertyKey(prop) is performed once");
+assert.sameValue(base.p, 2, "the result is assigned to the converted key");