[BlackBerry] Use APIEntryShim when making JS call
https://bugs.webkit.org/show_bug.cgi?id=110787

Reviewed by Rob Buis.

PR# 301451.
Use APIEntryShim to fix an assert and ensure it is thread-safe.

* Api/WebPage.cpp:
(BlackBerry::WebKit::WebPage::executeJavaScriptFunction):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@144069 268f45cc-cd09-0410-ab3c-d52691b4dbfc