MutationObserver: Align validation of observe options to the spec

The spec now allows leaving out attributes when attributeOldValue
or attributeFilter. Same goes for characterData and
characterDataOldValue.

The errors should be TypeErrors and not SyntaxErrors (this is not
syntax).

http://dom.spec.whatwg.org/#dom-mutationobserver-observe

BUG=314632

Review URL: https://codereview.chromium.org/58203003

git-svn-id: svn://svn.chromium.org/blink/trunk@161925 bbb929c8-8fbe-4397-9dbb-9b2b20218538