add test for modern compound assignment in js/implicit-operand-conversion

Author: erik-krogh

javascript/ql/test/query-tests/Expressions/ImplicitOperandConversion/ImplicitOperandConversion.expected

@@ -13,3 +13,5 @@
 | tst.js:106:5:106:7 | g() | This expression will be implicitly converted from undefined to number. |
 | tst.js:109:13:109:15 | g() | This expression will be implicitly converted from undefined to number. |
 | tst.js:110:13:110:15 | g() | This expression will be implicitly converted from undefined to string. |
+| tst.js:117:8:117:8 | y | This expression will be implicitly converted from string to number. |
+| tst.js:122:10:122:10 | y | This expression will be implicitly converted from string to number. |

javascript/ql/test/query-tests/Expressions/ImplicitOperandConversion/tst.js

@@ -110,3 +110,14 @@ function l() {
     var b = g() + "str";
 });
 
+
+function m() {
+  var x = 19, y = "string";
+  
+  x %= y; // NOT OK
+  x += y; // OK 
+  x ||= y; // OK
+  x &&= y; // OK
+  x ??= y; // OK
+  x >>>= y; // NOT OK
+}