selectAllChildren method specifies that it selects characters if passed a text node

[darinadler]

The selectAllChildren method steps indicate that the range should be created with the node and the length of the that node. However, the current version of web platform tests, the function’s name, and the WebKit engine all agree that this should select only children, not text node characters. I’m guessing that the web-compatible behavior is also the behavior that makes logical sense given name’s explicit mention of children. Instead of using the length of the node the algorithm should use the node’s number of children.