[Cocoa] -[WKWebProcessPlugInController parameters] returns nil if no parameters have been set yet
https://bugs.webkit.org/show_bug.cgi?id=132223

Reviewed by Sam Weinig.

* WebProcess/InjectedBundle/mac/InjectedBundleMac.mm:
(WebKit::InjectedBundle::bundleParameters): Create the WKWebProcessBundleParameters if
needed.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@167865 268f45cc-cd09-0410-ab3c-d52691b4dbfc