Revert "[vm] Deep clone context when cloning closure"
Revert "[vm] Deep clone context when cloning closure"

This reverts commit 61b5ba7ecf431a736ebaa3520f815fea92cabfa7.

Reason for revert: found a counter-example for deep cloning: https://dart-review.googlesource.com/c/sdk/+/70681

Original change's description:
> [vm] Deep clone context when cloning closure
> 
> _SyncIterable::iterator clones unerlying sync* closure to create a new
> Iterator using _Closure._clone(). _Closure._clone() was cloning only
> 1 level of context, relying on a particular context structure.
> 
> In bytecode, contexts are allocated in a different way, so sync*
> functions could have more then 1 level of contexts. In such case,
> parent contexts were not cloned in _Closure._clone() and were shared
> between Iterator instances.
> 
> This CL adds deep cloning of contexts into _Closure._clone() native method
> in order to handle arbitrary number of levels of contexts in a closure.
> 
> Fixes language_2/syncstar_yield_test test in bytecode mode.
> 
> Change-Id: Ic5ced4c32fc2e21726db76608cd3a7db7e553472
> Reviewed-on: https://dart-review.googlesource.com/70600
> Reviewed-by: Régis Crelier <regis@google.com>
> Commit-Queue: Alexander Markov <239e774fd29abc1267878f57afe1a8a03e0ca887@google.com>

TBR=rmacnak@google.com,239e774fd29abc1267878f57afe1a8a03e0ca887@google.com,regis@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Change-Id: I9f6116069cbec022ad86ef4cbf6801c603b4ab15
Reviewed-on: https://dart-review.googlesource.com/70700
Reviewed-by: Alexander Markov <239e774fd29abc1267878f57afe1a8a03e0ca887@google.com>
Commit-Queue: Alexander Markov <239e774fd29abc1267878f57afe1a8a03e0ca887@google.com>

dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk