Revert of Set the javac target and source to 1.7

Revert of Set the javac target and source to 1.7 (patchset #2 id:20001 of https://chromiumcodereview.appspot.com/545363002/)

Reason for revert:
Not all bots have Java 7 yet :(

Original issue's description:
> Set the javac target and source to 1.7
>
> BUG=336589
> TBR=yfriedman@chromium.org
>
> Committed: https://crrev.com/165c0f17fe5760a3f346940d4fb2574d62cfe53b
> Cr-Commit-Position: refs/heads/master@{#295162}

TBR=cjhopman@chromium.org,yfriedman@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=336589
Committed: https://crrev.com/094138696e943744d1489ebb98276b116eafed99
Cr-Commit-Position: refs/heads/master@{#295165}

[aurimas (slooooooooow), 2014-09-16 22:47:26]

Created Revert of Set the javac target and source to 1.7

[commit-bot: I haz the power, 2014-09-16 22:48:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/579543003/1

[commit-bot: I haz the power, 2014-09-16 22:49:40]

Committed patchset #1 (id:1) as d0d537826cdfbe3cf468467f5ece78b4a52979cc

[commit-bot: I haz the power, 2014-09-16 22:50:32]

Patchset 1 (id:??) landed as
https://crrev.com/094138696e943744d1489ebb98276b116eafed99
Cr-Commit-Position: refs/heads/master@{#295165}

[aurimas (slooooooooow), 2014-09-25 01:23:55]

A revert of this CL (patchset #1 id:1) has been created in
https://chromiumcodereview.appspot.com/601983002/ by aurimas@chromium.org.

The reason for reverting is: All the bots have been switched to Java 7 according
to https://code.google.com/p/chromium/issues/detail?id=411503#c19.