Break core/platform/network dependency on core

Break core/platform/network dependency on core

This CL breaks the last dependency from core/platform/network to the rest of
core. I've moved FormDataList back to core and made it responsible for building
FormData objects out of Blobs (and other items). That means FormData is not
just data, which makes sense.

After this CL and https://codereview.chromium.org/26283005/ land, we'll be able
to move core/platform/network into blink_platform.dll.

R=eseidel@chromium.org, eseidel
BUG=297477
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=159951

[eseidel, 2013-10-17 22:36:09]

lgtm

[commit-bot: I haz the power, 2013-10-17 22:42:29]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/abarth@chromium.org/27537012/1

[commit-bot: I haz the power, 2013-10-17 23:49:02]

Failed to trigger a try job on win_layout
HTTP Error 400: Bad Request

[commit-bot: I haz the power, 2013-10-17 23:49:11]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/abarth@chromium.org/27537012/2001

[commit-bot: I haz the power, 2013-10-18 08:27:30]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/abarth@chromium.org/27537012/2001

[abarth-chromium, 2013-10-18 15:52:09]

Committed patchset #2 manually as r159951 (presubmit successful).