This patch:
- adds input methods to ElementHandle, such as ElementHandle.type and ElementHandle.press
- changes `page.type` to accept selector as the first argument
- removes `page.press` method. The `page.press` is rarely used and doesn't operate with selectors; if there's a need to press a button, `page.keyboard.press` should be used.
BREAKING CHANGE: `page.type` is changed, `page.press` is removed.
Fixes#241.
0af0d7dba5