Add resolve(void) and reject(void) to ScriptPromiseResolver.

They are abbreviations for resolve(undefined) and reject(undefined).

BUG=390894

Review URL: https://codereview.chromium.org/363253002

git-svn-id: svn://svn.chromium.org/blink/trunk@177904 bbb929c8-8fbe-4397-9dbb-9b2b20218538