Revert of Remove webkitConvertPointFromPageToNode() and webkitConvertPointFromNodeToPage()

Revert of Remove webkitConvertPointFromPageToNode() and webkitConvertPointFromNodeToPage() (patchset #1 of https://codereview.chromium.org/428533003/)

Reason for revert:
Wait for WebKitPoint use counter data and remove them together:
https://groups.google.com/a/chromium.org/d/msg/blink-dev/KS5GAM7JXtg/AXNh8otMw8MJ

Original issue's description:
> Remove webkitConvertPointFromPageToNode() and webkitConvertPointFromNodeToPage()
> 
> Intent to Deprecate and Remove:
> https://groups.google.com/a/chromium.org/d/msg/blink-dev/KS5GAM7JXtg/7KyhsqQFZMkJ
> 
> BUG=398352
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=179135

BUG=398352

[philipj_slow, 2014-08-29 09:30:16]

Created Revert of Remove webkitConvertPointFromPageToNode() and
webkitConvertPointFromNodeToPage()

[philipj_slow, 2014-08-29 11:57:33]

rebase

[philipj_slow, 2014-08-29 13:19:45]

philipj@opera.com changed reviewers:
+ eseidel@chromium.org
- jochen@chromium.org

[philipj_slow, 2014-08-29 13:19:45]

PTAL. No API owner chimed in on blink-dev, so I'm playing it safe.

[philipj_slow, 2014-08-29 19:49:57]

Please hold the review on this. Since you expressed a preference for removing
WebKitPoint on blink-dev and that's also what I'd prefer I'll sent an intent to
do just that.