[turbofan] Remove RepresentationChanger::simplified field.

[turbofan] Remove RepresentationChanger::simplified field.

R=mvstanton@chromium.org

Committed: https://crrev.com/4c0d4b71f79794bfd5e06c253801c8f000bca9f0
Cr-Commit-Position: refs/heads/master@{#31569}

[Michael Starzinger, 2015-10-26 13:15:17]

Context: The simplified operator builder is now reachable through the JSGraph.
This is a small follow-up cleanup that I stumbled across.

[mvstanton, 2015-10-26 13:22:32]

velly nice, lgtm.

[Michael Starzinger, 2015-10-26 13:40:44]

The CQ bit was checked by mstarzinger@chromium.org

[Michael Starzinger, 2015-10-26 13:40:45]

The patchset sent to the CQ was uploaded after l-g-t-m from
mvstanton@chromium.org
Link to the patchset: https://codereview.chromium.org/1425643002/#ps2 (title:
"Small fix.")

[commit-bot: I haz the power, 2015-10-26 13:40:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1425643002/2
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1425643002/2

[commit-bot: I haz the power, 2015-10-26 14:29:18]

Committed patchset #2 (id:2)

[commit-bot: I haz the power, 2015-10-26 14:29:46]

Patchset 2 (id:??) landed as
https://crrev.com/4c0d4b71f79794bfd5e06c253801c8f000bca9f0
Cr-Commit-Position: refs/heads/master@{#31569}