[turbofan] Reduce Float64 comparison to Float32.

[turbofan] Reduce Float64 comparison to Float32.

Reduce Float64 comparison to Float32 when both inputs are conversions from
Float32.

Committed: https://crrev.com/ad7f35c49aa94b2bc625fe59a5e9251ef2645889
Cr-Commit-Position: refs/heads/master@{#29586}

[martyn.capewell, 2015-07-10 16:52:00]

martyn.capewell@arm.com changed reviewers:
+ bmeurer@chromium.org, ulan@chromium.org

[martyn.capewell, 2015-07-10 16:52:00]

This currently brings a little performance on the Jetstream gcc-loops benchmark,
and seems like a cheap optimisation to make, but it may go away when benchmarks
are recompiled with better support for Float32 ops.

[Benedikt Meurer, 2015-07-13 04:38:52]

LGTM.

[Benedikt Meurer, 2015-07-13 04:38:56]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-07-13 04:39:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1235663002/1

[commit-bot: I haz the power, 2015-07-13 04:39:13]

The author martyn.capewell@arm.com has not signed Google Contributor License
Agreement. Please visit https://cla.developers.google.com to sign and manage
CLA.

[commit-bot: I haz the power, 2015-07-13 05:00:46]

The author martyn.capewell@arm.com has not signed Google Contributor License
Agreement. Please visit https://cla.developers.google.com to sign and manage
CLA.

[commit-bot: I haz the power, 2015-07-13 05:23:46]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-13 05:24:05]

Patchset 1 (id:??) landed as
https://crrev.com/ad7f35c49aa94b2bc625fe59a5e9251ef2645889
Cr-Commit-Position: refs/heads/master@{#29586}