Rename the HolderContainer template parameter to CallbackInfo.

The templatized functions are called with PropertyCallbackInfo or
FunctionCallbackInfo. So it's clearer to call the template parameter
CallbackInfo than HolderContainer. (What does HolderContainer mean?)

BUG=

Review URL: https://chromiumcodereview.appspot.com/19204002

git-svn-id: svn://svn.chromium.org/blink/trunk@154232 bbb929c8-8fbe-4397-9dbb-9b2b20218538