Do not hide context menu if it showing from image in editable content.

Do not hide context menu if it showing from image in editable content.

[Title] Do not hide context menu if it showing from image in editable content.
[Issue#] DCM-2134
[Problem]
1. Context menu disappear after tab end if it showing from image in editable content
2. Focus ring doesn't hide after tab end if before context menu is shown
[Cause]
1. In case of image and link, context menu is showing before end tab so when endtap is called it makes textselection mode to false
2. Don't hide focus ring if context menu was shown before
[Solution]
1. Don't show context menu if hittest result data is contentEditable in start gesture
2. Hide focus ring if textSelectionMode is true in end gesture

Change-Id: I4c2e0a9ee4cfb82c4cd88447ee8d90d5c339bed1