Tokenizer/PHP: document handling of \true/\false/\null

The handling as documented here is 100% in line with the way PHP 8.0+ handles this natively.

Author: jrfnl

tests/Core/Tokenizers/PHP/NamespacedNameSingleTokenTest.inc

@@ -133,6 +133,15 @@ class MyClass
 
         /* testInstanceOfPartiallyQualified */
         $is = $obj instanceof Partially\ClassName;
+
+        /* testFullyQualifiedNull */
+        $a = \NULL;
+
+        /* testFullyQualifiedFalse */
+        $a = \false;
+
+        /* testFullyQualifiedTrue */
+        $a = \True;
     }
 }
 

tests/Core/Tokenizers/PHP/NamespacedNameSingleTokenTest.php

@@ -868,6 +868,45 @@ public static function dataIdentifierTokenization()
                     ],
                 ],
             ],
+            'fully qualified "null"'                                                                      => [
+                'testMarker'     => '/* testFullyQualifiedNull */',
+                'expectedTokens' => [
+                    [
+                        'type'    => 'T_NAME_FULLY_QUALIFIED',
+                        'content' => '\NULL',
+                    ],
+                    [
+                        'type'    => 'T_SEMICOLON',
+                        'content' => ';',
+                    ],
+                ],
+            ],
+            'fully qualified "false"'                                                                     => [
+                'testMarker'     => '/* testFullyQualifiedFalse */',
+                'expectedTokens' => [
+                    [
+                        'type'    => 'T_NAME_FULLY_QUALIFIED',
+                        'content' => '\false',
+                    ],
+                    [
+                        'type'    => 'T_SEMICOLON',
+                        'content' => ';',
+                    ],
+                ],
+            ],
+            'fully qualified "true"'                                                                      => [
+                'testMarker'     => '/* testFullyQualifiedTrue */',
+                'expectedTokens' => [
+                    [
+                        'type'    => 'T_NAME_FULLY_QUALIFIED',
+                        'content' => '\True',
+                    ],
+                    [
+                        'type'    => 'T_SEMICOLON',
+                        'content' => ';',
+                    ],
+                ],
+            ],
             'function call, namespace relative, with whitespace (invalid in PHP 8)'                       => [
                 'testMarker'     => '/* testInvalidInPHP8Whitespace */',
                 'expectedTokens' => [