[wasm] New attempt to implement the Int64Lowering of phis.

[wasm] New attempt to implement the Int64Lowering of phis.

The new implementation deals with cycles in the TF graph in two steps:
1) The lowering of phis is delayed to avoid cyclic dependencies.
2) The replacement nodes of phis are created already when the phi is
   pushed onto the stack so that other nodes can use these replacements
   for their lowering.

R=titzer@chromium.org

Committed: https://crrev.com/682df6dd331a434f6064867de6ef0043c9dbcda4
Cr-Commit-Position: refs/heads/master@{#35126}

[titzer, 2016-03-29 16:09:44]

lgtm this is so much cleaner! love it!

[ahaas, 2016-03-30 08:11:39]

The CQ bit was checked by ahaas@chromium.org

[commit-bot: I haz the power, 2016-03-30 08:11:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1844553002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1844553002/20001

[commit-bot: I haz the power, 2016-03-30 08:13:56]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-03-30 08:14:41]

Description was changed from

==========
[wasm] New attempt to implement the Int64Lowering of phis.

The new implementation deals with cycles in the TF graph in two steps:
1) The lowering of phis is delayed to avoid cyclic dependencies.
2) The replacement nodes of phis are created already when the phi is
   pushed onto the stack so that other nodes can use these replacements
   for their lowering.

R=titzer@chromium.org
==========

to

==========
[wasm] New attempt to implement the Int64Lowering of phis.

The new implementation deals with cycles in the TF graph in two steps:
1) The lowering of phis is delayed to avoid cyclic dependencies.
2) The replacement nodes of phis are created already when the phi is
   pushed onto the stack so that other nodes can use these replacements
   for their lowering.

R=titzer@chromium.org

Committed: https://crrev.com/682df6dd331a434f6064867de6ef0043c9dbcda4
Cr-Commit-Position: refs/heads/master@{#35126}
==========

[commit-bot: I haz the power, 2016-03-30 08:14:42]

Patchset 2 (id:??) landed as
https://crrev.com/682df6dd331a434f6064867de6ef0043c9dbcda4
Cr-Commit-Position: refs/heads/master@{#35126}