Do not attempt to read language mode from {,Strict}{,Not}Equal nodes.

Do not attempt to read language mode from {,Strict}{,Not}Equal nodes.

We were previously reading a language mode from all comparison nodes
in JSGenericLowering::ReplaceWithCompareIC. This read was invalid for
{,Strict}{,Not}Equal nodes, as these nodes do not have a language mode, as they
derive from Operator rather than from Operator1<LanguageMode>. Because these
nodes are not language mode dependent, we arbitrarily pass Strength::WEAK
to CodeFactory::CompareIC.

Cleanup for cfi_vptr=1; see https://www.chromium.org/developers/testing/control-flow-integrity

BUG=chromium:457523
R=bmeurer@chromium.org
LOG=N

Committed: https://crrev.com/09bb401b803eef0f2c6afa104d8ff80d821d9d61
Cr-Commit-Position: refs/heads/master@{#30491}

[Benedikt Meurer, 2015-09-01 04:04:40]

LGTM

[pcc1, 2015-09-01 04:15:58]

The CQ bit was checked by pcc@chromium.org

[commit-bot: I haz the power, 2015-09-01 04:16:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1319463003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1319463003/1

[commit-bot: I haz the power, 2015-09-01 04:41:33]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-01 04:41:45]

Patchset 1 (id:??) landed as
https://crrev.com/09bb401b803eef0f2c6afa104d8ff80d821d9d61
Cr-Commit-Position: refs/heads/master@{#30491}