fixes crash in utc_blink_ewk_view_javascript_confirm_reply_func test

fixes crash in utc_blink_ewk_view_javascript_confirm_reply_func test

When calling ewk_view_javascript_confirm_reply, the close dialog
callback is executed. But if returning false from
ewk_view_javascript_confirm_callback_set, the close dialog callback is
also executed.

So, we need to return EINA_TRUE from confirmCallback; otherwise, the
close dialog callback is executed twice, which leads to a crash.

Bug: http://107.108.218.239/bugzilla/show_bug.cgi?id=6980

Reviewed by: a1.gomes, g.czajkowski

Change-Id: I7a7300161a52e5180ae52f82301d478d203a2cdd
Signed-off-by: Arnaud Renevier <a.renevier@samsung.com>