Store form control list with RefPtr.

FormController needs to keep a list of HTMLFormControlElementWithState in the
Document. We used raw pointers, and switch to RefPtrs by this CL to avoid

Also, we don't need to keep controls not in the Document tree and controls in
shadow trees. So we change timing to register/unregister form controls.


Review URL:

git-svn-id: svn:// bbb929c8-8fbe-4397-9dbb-9b2b20218538
6 files changed