Revert of Add a separate scope for switch (patchset #7 id:120001 of https://codereview.chromium.org/1293283002/ )

Reason for revert:
Breaks cctest/test-cpu-profiler/SourceLocation on nosnap

Original issue's description:
> 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.
>
> BUG=v8:4377
> LOG=Y
> R=adamk
>
> Committed: https://crrev.com/9edbc1f21eb1050cabbe3b8bc9aebf89ada7ebd7
> Cr-Commit-Position: refs/heads/master@{#30314}

TBR=adamk@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4377

Review URL: https://codereview.chromium.org/1309043004

Cr-Commit-Position: refs/heads/master@{#30316}