The patch converts all the getters in the codebase into the methods.
For example, the `request.url` getter becomes the `request.url()`
method.
This is done in order to unify the API and make it more predictable.
The general rule for all further changes would be:
- there are no getters/fields exposed in the api
- the only exceptions are "namespaces", e.g. `page.keyboard`
Fixes#280.
BREAKING CHANGE:
This patch ditches getters and replaces them with methods throughout
the API. The following methods were added instead of the fields:
- dialog.type()
- consoleMessage.args()
- consoleMessage.text()
- consoleMessage.type()
- request.headers()
- request.method()
- request.postData()
- request.resourceType()
- request.url()
- response.headers()
- response.ok()
- response.status()
- response.url()