Add a separate scope for switch

Add a separate scope for switch

The ES2015 specification for switch statements 13.12.11 specifies that
they get their own lexical scope. This patch introduces such a scope
through a complex desugaring in terms of blocks, done so that Crankshaft
does not have to be updated to support multiple constructs providing
scopes.

Recommitting this patch after a bug fix in Crankshaft to allow a
desugaring with certain elements missing a source location:
https://codereview.chromium.org/1313443002

BUG=v8:4377
LOG=Y
R=adamk

Committed: https://crrev.com/45e2628df7bc4151a893f38794014082e0b269d5
Cr-Commit-Position: refs/heads/master@{#30340}

[adamk, 2015-08-24 18:13:34]

lgtm

[Dan Ehrenberg, 2015-08-24 18:17:13]

The CQ bit was checked by littledan@chromium.org

[commit-bot: I haz the power, 2015-08-24 18:17:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1309163003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1309163003/1

[commit-bot: I haz the power, 2015-08-24 18:27:15]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-24 18:27:16]

Try jobs failed on following builders:
  v8_mac_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_mac_rel/builds/8995)

[Dan Ehrenberg, 2015-08-24 18:31:26]

The CQ bit was checked by littledan@chromium.org

[Dan Ehrenberg, 2015-08-24 18:31:27]

The patchset sent to the CQ was uploaded after l-g-t-m from adamk@chromium.org
Link to the patchset: https://codereview.chromium.org/1309163003/#ps20001
(title: "Avoid arrow function in test")

[commit-bot: I haz the power, 2015-08-24 18:31:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1309163003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1309163003/20001

[commit-bot: I haz the power, 2015-08-24 18:57:13]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-08-24 18:57:31]

Patchset 2 (id:??) landed as
https://crrev.com/45e2628df7bc4151a893f38794014082e0b269d5
Cr-Commit-Position: refs/heads/master@{#30340}