Implement missing LocalObject functions.

LocalObject is declared to extend RemoteObject, but doesn't implement
callFunction and callFunctionJSON.

BUG=144646

Review URL: https://codereview.chromium.org/101753002

git-svn-id: svn://svn.chromium.org/blink/trunk@163227 bbb929c8-8fbe-4397-9dbb-9b2b20218538