Contents of Magnifier are getting truncated

Contents of Magnifier are getting truncated

[Title] Contents of Magnifier are getting truncated
[Issue#] N_SE-44325
[Problem] If the touch point is at the top or at the bottom
   end during extending the selection then the contents in
   the magnifier are not visible correctly
[Cause] The rect sent to get the snapshot of the page is
   above the visable area so text appears to be truncated
[Solution] Added check if the touch point is very near to
   top or bottom then adjust the content rect

Change-Id: I248d7b0886347dc80f6ad81e2a17d218228803e3