Resized Text area in ReplaceText extension

Given these fields 100% width and, say, 25 or more rows
for easy editing of text. This is important due to the
risk of overlooking mistakes if all the text is not visible.
patch courtsey: Pranav Ravichandran

Bug: 32894
Change-Id: I08f36d5c581ea4b0429f88899830ea0868407435