Add a missing null check to LinkStyle::process()

This is a speculative fix for crashes that are reported from wild.

BUG=358844
R=esprehn@chromium.org

Review URL: https://codereview.chromium.org/220723012

git-svn-id: svn://svn.chromium.org/blink/trunk@170689 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/html/HTMLLinkElement.cpp

@@ -627,7 +627,7 @@ void LinkStyle::process()
             return;
         if (!document().contentSecurityPolicy()->allowImageFromSource(builder.url()))
             return;
-        if (document().frame())
+        if (document().frame() && document().frame()->loader().client())
             document().frame()->loader().client()->dispatchDidChangeIcons(m_owner->relAttribute().iconType());
     }