Split out const/non-const variants of Resource::resourceRequest().

Split out  const/non-const variants of Resource::resourceRequest().

This patch follows the general convention of *::resourceRequest() and
*::mutableResourceRequest() from various other classes which use
ResourceRequest objects (FetchRequest, NavigationAction, etc).

As a drive-by, it also consts Resource::lastResourceRequest(), which was
already returning a const reference.

NOTRY=true

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=179143

[Mike West, 2014-07-29 10:59:45]

Mind taking a quick look at this cleanup CL?

[jochen (gone - plz use gerrit), 2014-07-29 11:26:51]

lgtm

[Mike West, 2014-07-29 11:42:09]

The CQ bit was checked by mkwst@chromium.org

[commit-bot: I haz the power, 2014-07-29 11:42:57]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mkwst@chromium.org/424083002/1

[Mike West, 2014-07-29 12:59:53]

The CQ bit was unchecked by mkwst@chromium.org

[Mike West, 2014-07-29 13:00:06]

The CQ bit was checked by mkwst@chromium.org

[commit-bot: I haz the power, 2014-07-29 13:00:16]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mkwst@chromium.org/424083002/1

[commit-bot: I haz the power, 2014-07-29 13:00:47]

Change committed as 179143