doc: Sync classref with current source

doc/classes/Theme.xml

@@ -278,7 +278,7 @@
 			</description>
 		</method>
 		<method name="get_theme_item" qualifiers="const">
-			<return type="StyleBox">
+			<return type="Variant">
 			</return>
 			<argument index="0" name="data_type" type="int" enum="Theme.DataType">
 			</argument>

scene/resources/theme.cpp

@@ -1371,12 +1371,12 @@ void Theme::_bind_methods() {
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "default_font", PROPERTY_HINT_RESOURCE_TYPE, "Font"), "set_default_font", "get_default_font");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "default_font_size"), "set_default_font_size", "get_default_font_size");
 
-	BIND_ENUM_CONSTANT(DATA_TYPE_ICON);
-	BIND_ENUM_CONSTANT(DATA_TYPE_STYLEBOX);
-	BIND_ENUM_CONSTANT(DATA_TYPE_FONT);
-	BIND_ENUM_CONSTANT(DATA_TYPE_FONT_SIZE);
 	BIND_ENUM_CONSTANT(DATA_TYPE_COLOR);
 	BIND_ENUM_CONSTANT(DATA_TYPE_CONSTANT);
+	BIND_ENUM_CONSTANT(DATA_TYPE_FONT);
+	BIND_ENUM_CONSTANT(DATA_TYPE_FONT_SIZE);
+	BIND_ENUM_CONSTANT(DATA_TYPE_ICON);
+	BIND_ENUM_CONSTANT(DATA_TYPE_STYLEBOX);
 	BIND_ENUM_CONSTANT(DATA_TYPE_MAX);
 }