REGRESSION (r106681): Null check missing in [WebFrame(WebInternal) _typingStyle]

REGRESSION (r106681): Null check missing in [WebFrame(WebInternal) _typingStyle]
https://bugs.webkit.org/show_bug.cgi?id=78080

Source/WebKit/mac:

Reviewed by Reviewed by Andreas Kling, Darin Adler and Dan Bernstein.

* WebView/WebFrame.mm:
(-[WebFrame _typingStyle]):

Tools:

Reviewed by Andreas Kling, Darin Adler and Dan Bernstein.

Add API test.

* TestWebKitAPI/TestWebKitAPI.xcodeproj/project.pbxproj:
* TestWebKitAPI/Tests/mac/TypingStyleCrash.mm: Added.
(TestWebKitAPI):
(TestWebKitAPI::TEST):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@107100 268f45cc-cd09-0410-ab3c-d52691b4dbfc