Element Send Keys should not use a new line character as separator for multiple files

Currently the remote steps for "Element Send Keys" allow to set multiple files which then are splitted by new line (\n):

https://w3c.github.io/webdriver/#dfn-element-send-keys

Let files be the result of splitting text on the newline (\n) character.

This is actually broken because some operating systems allow to use new line characters in the filename. Here an example from MacOS:

% touch "foo
\ bar"

% ls
'foo'$'\n''bar'

I discussed this with @andreastt and maybe we should better allow only one file per Element Send Keys invocation, given that there doesn't seem to exist a stable separator across platforms.

Not sure how other drivers are working in regards of that feature. @jimevans mind giving some feedback for IEDriver?

Start with the Element Send Keys section of the WebDriver specification linked in the issue, focusing on how multiple files are split on newline characters. Review the reported MacOS filename example and the requested feedback about other drivers, including IEDriver. Done requires an agreed cross-platform behavior and a corresponding specification change.