Fix Qt 5.3 backward compatible build

The accelerated canvas and dynamic GL support used Qt 5.4 specific
features. These can be avoided by disabling one webgl extension and
being less efficient in accelerated canvas, thereby making it possible
to still build QtWebKit with Qt 5.3.

Change-Id: Ic64f7f5ac6b836b314331c4d509e4d64cb0dcb7c
Reviewed-by: Michael Bruning <michael.bruning@digia.com>
Remove QtScript includes

Remove QtScript includes that haven't been usedin years.

Change-Id: Iea2b61a6ad2ea187055daff783ce9f0280477767
Reviewed-by: Michael Bruning <michael.bruning@digia.com>