Fix OS singleton being incorrectly highlighted as a constant (#402)

syntaxes/GDScript.tmLanguage.json

@@ -485,7 +485,7 @@
             }
         },
         "builtin_classes": {
-            "match": "(?<![^.]\\.|:)\\b(Vector2|Vector2i|Vector3|Vector3i|Color|Rect2|Rect2i|Array|Basis|Dictionary|Plane|Quat|RID|Rect3|Transform|Transform2D|Transform3D|AABB|String|Color|NodePath|Object|PoolByteArray|PoolIntArray|PoolRealArray|PoolStringArray|PoolVector2Array|PoolVector3Array|PoolColorArray|bool|int|float|StringName|Quaternion|PackedByteArray|PackedInt32Array|PackedInt64Array|PackedFloat32Array|PackedFloat64Array|PackedStringArray|PackedVector2Array|PackedVector2iArray|PackedVector3Array|PackedVector3iArray|PackedColorArray)\\b",
+            "match": "(?<![^.]\\.|:)\\b(OS|Vector2|Vector2i|Vector3|Vector3i|Color|Rect2|Rect2i|Array|Basis|Dictionary|Plane|Quat|RID|Rect3|Transform|Transform2D|Transform3D|AABB|String|Color|NodePath|Object|PoolByteArray|PoolIntArray|PoolRealArray|PoolStringArray|PoolVector2Array|PoolVector3Array|PoolColorArray|bool|int|float|StringName|Quaternion|PackedByteArray|PackedInt32Array|PackedInt64Array|PackedFloat32Array|PackedFloat64Array|PackedStringArray|PackedVector2Array|PackedVector2iArray|PackedVector3Array|PackedVector3iArray|PackedColorArray)\\b",
             "name": "support.class.library.gdscript"
         },
         "const_vars": {

syntaxes/examples/gdscript1.gd

@@ -221,3 +221,8 @@ class InnerClass:
 			pass
 		
 		pass
+
+# ------------------------------------------------------------------------------
+
+func test_function():
+	OS.get_name()