Remove uses of const in distiller javascript

Remove uses of const in distiller javascript

Using the 'const' keyword in javascript breaks distiller on iOS. This
change removes those instances and replaces them with var.

BUG=

Committed: https://crrev.com/b0477dae6747caf7b8da9831feef8154f72868e3
Cr-Commit-Position: refs/heads/master@{#330966}

[mdjones, 2015-05-20 16:58:12]

mdjones@chromium.org changed reviewers:
+ wychen@chromium.org

[mdjones, 2015-05-20 16:58:13]

This is one option for the fix, the other involves removing the 'use strict' at
the top of that function.

[wychen, 2015-05-20 18:20:59]

Oops. Forgot about iOS. LGTM.

[mdjones, 2015-05-20 18:29:52]

mdjones@chromium.org changed reviewers:
+ nyquist@chromium.org

[mdjones, 2015-05-20 18:29:52]

+nyquist for owner approval.

[nyquist, 2015-05-21 05:42:48]

lgtm

[mdjones, 2015-05-21 15:53:22]

The CQ bit was checked by mdjones@chromium.org

[commit-bot: I haz the power, 2015-05-21 15:54:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1148083003/1

[commit-bot: I haz the power, 2015-05-21 18:00:04]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-05-21 18:00:05]

Try jobs failed on following builders:
  android_clang_dbg_recipe on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/android_clang_d...)

[mdjones, 2015-05-21 18:21:26]

The CQ bit was checked by mdjones@chromium.org

[commit-bot: I haz the power, 2015-05-21 18:23:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1148083003/1

[commit-bot: I haz the power, 2015-05-21 20:30:40]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-21 20:33:17]

Patchset 1 (id:??) landed as
https://crrev.com/b0477dae6747caf7b8da9831feef8154f72868e3
Cr-Commit-Position: refs/heads/master@{#330966}