Convert some of the subobjects of context2d to v4

Change-Id: I0ad5b466e65da41a7acf8a0a89e7cf26ce2df76d
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Convert the instance methods of context2d to v4

Change-Id: Ic2b80ab828a0f96a72850b0672f5c085a4cfae0a
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>