Revert of [ServiceWorker] Make Response class better conformance with the spec. (https://codereview.chromium.org/373613004/)

Reason for revert:
Broke content_browsertests

http://build.chromium.org/p/chromium.webkit/builders/Linux%20Tests/builds/37860

ServiceWorkerVersionBrowserTest.FetchEvent_Response
ServiceWorkerBrowserTest.Reload


Original issue's description:
> [ServiceWorker] Make Response class better conformance with the spec.
> 
> In current implementation Response class only supports status, statusText, and headers attributes.
> This change introduce type, url attributes and change the class of headers attribute from HeaderMap to Headers and make all attributes readonly.
> And also this change implements the logic which is defined in the spec.
> 
> http://fetch.spec.whatwg.org/#response-class 
> http://fetch.spec.whatwg.org/#response
> 
> 
> This cl depends on http://crrev.com/329853012 and http://crrev.com/370733002
> 
> BUG=373120
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=177793

TBR=falken@chromium.org,haraken@chromium.org,tkent@chromium.org,horo@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=373120

Review URL: https://codereview.chromium.org/383653002

git-svn-id: svn://svn.chromium.org/blink/trunk@177803 bbb929c8-8fbe-4397-9dbb-9b2b20218538