[selection-api] Need to be able to tell if the caret is displayed at the beginning or the end of the line (#32)

If a caret is at the end of a line that wraps, it's hard to tell where it is on the screen (end of line or beginning of the next line). This is important for being able to control the selection (beforeSelectionChange).

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/selection-api/issues/32