Add tests for list() in assignment in array literals

Array literals will constant evaluate their elements. These can include
assignments, even though these are not valid constant expressions. The lhs of
assignments can be a list() element (or []) which is parsed as an array with a
special flag.

Author: iluuu1994

Zend/tests/gh11320_1.phpt

@@ -0,0 +1,28 @@
+--TEST--
+GH-11320: Array literals can contain list() assignments
+--FILE--
+<?php
+$index = 1;
+function getList() { return [2, 3]; }
+var_dump([$index => list($x, $y) = getList()]);
+var_dump([$index => [$x, $y] = getList()]);
+?>
+--EXPECT--
+array(1) {
+  [1]=>
+  array(2) {
+    [0]=>
+    int(2)
+    [1]=>
+    int(3)
+  }
+}
+array(1) {
+  [1]=>
+  array(2) {
+    [0]=>
+    int(2)
+    [1]=>
+    int(3)
+  }
+}

Zend/tests/gh11320_2.phpt

@@ -0,0 +1,12 @@
+--TEST--
+GH-11320: list() expressions can contain magic constants
+--FILE--
+<?php
+[list(__FILE__ => $foo) = [__FILE__ => 'foo']];
+var_dump($foo);
+[[__FILE__ => $foo] = [__FILE__ => 'foo']];
+var_dump($foo);
+?>
+--EXPECT--
+string(3) "foo"
+string(3) "foo"

Zend/tests/gh11320_3.phpt

@@ -0,0 +1,8 @@
+--TEST--
+GH-11320: list() must not appear as a standalone array element
+--FILE--
+<?php
+[list($a)];
+?>
+--EXPECTF--
+Fatal error: Cannot use list() as standalone expression in %s on line %d