[WK2] Fix for initial scale handling for mobile pages in UI process side.

[WK2] Fix for initial scale handling for mobile pages in UI process side.

[Version]    N/A
[Project]    N/A
[Title]      Fix for issue WEB-2446
[BinType]    N/A
[Customer]   N/A
[Issue#]     WEB-2446
[Problem]    [WK2] Page display differs while reloading the same webpage in "http://dev.bybjorn.com/ipadoffline".
[Cause]      Viewport's initial scale handling on UI process is at fault. In WebKit::PageClientImpl::didChangeContentsSize
             over-writes initilal scale and replaces it with minimumScaleByContentWidth, i.e. ratio of webview (evas object)
             size's width to page contents width. Apparently contents fit to width, instead of initial scale set in pages
             meta viewport tag.
[Solution]   If initialScale is not set explicitly in content's meta viewport and is same to minimumScale, then only
             update initialScale to the minimumScaleByContentWidth. Otherwise retain the initial scale to value specified in
             content's viewport consraints.
[Team]       TiledAC
[Developer]  pritam.nikam
[Request]    N/A
[Horizontal expansion] N/A
[SCMRequest] N/A

Change-Id: Iba9302bb9b0ffa22ea0c5d0e0d6a74c291211d3e