Simplify dispatch in FullCodeGenerator::VisitCall a bit.

Simplify dispatch in FullCodeGenerator::VisitCall a bit.

This makes FullCodeGenerator::VisitCall be independent of the target
architecture. Only the EmitPossiblyEvalCall case was dependent and is
hoisted into an emitter method.

R=rossberg@chromium.org

Committed: https://crrev.com/0b293d877ccc7155b54c485b3566514214110d47
Cr-Commit-Position: refs/heads/master@{#31693}

[Michael Starzinger, 2015-10-30 13:18:18]

Follow-up to one of my previous CLs as promised.

[rossberg, 2015-10-30 14:00:25]

lgtm

[ulan, 2015-10-30 14:31:49]

ulan@chromium.org changed reviewers:
+ ulan@chromium.org

[ulan, 2015-10-30 14:31:50]

arm64 part lgtm

[Michael Starzinger, 2015-10-30 14:34:36]

The CQ bit was checked by mstarzinger@chromium.org

[commit-bot: I haz the power, 2015-10-30 14:34:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1428953002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1428953002/20001

[commit-bot: I haz the power, 2015-10-30 14:42:09]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-10-30 14:42:26]

Patchset 2 (id:??) landed as
https://crrev.com/0b293d877ccc7155b54c485b3566514214110d47
Cr-Commit-Position: refs/heads/master@{#31693}