Load file:-URLs in the main thread.

QtWebKit does not support file:-URLs in Web Workers.
To solve this issue, I'm loading file:-URLs in the main thread
for generic builds. file:-URLs load relatively quick, so there
is no need for sophisticated load progress notifications.
Merge pull request #5100 from Rob--W/load-file-in-main-thread

Load file:-URLs in the main thread.
Fixes text-selection example
Merge pull request #5142 from yurydelendik/fix-ts-example

Fixes text-selection example
Simplify text-selection example.
Merge pull request #5143 from yurydelendik/fix-ts-example

Simplify text-selection example.