When saved mht file is opened progress bar is stuck

When saved mht file is opened progress bar is stuck

[Title] Saved mht file does not finish load if it has external resource in it
[Issue#] TD-9485
[Problem] When saved mht file is loaded the progress bar gets stuck and loading never finishes
[Cause] It happens when external resources i.e. resources not present in the mht resource file
        are included. Webkit tries to fail the load for such sub resources but this does not
        clear the sub resource loaders since didFail is never called and in the process
        checkLoadComplete is never called thereby keeping the load in an unfinished state
        infinitely.
[Solution] Allow external resources to be downloaded from network so as not to have a broken
           page. If external resources cannot be fetched didFail will be properly called and
           load will finish.
[Developer] Praveen (praveen.ks@samsung.com)