Rework type inference of assignments to index expressions.

Rework type inference of assignments to index expressions.

The approach from the las CL (try to figure out the structure of the
assignment expression from the desugared result) turned out to be
unsustainably complex.  In this version we keep track of the structure
while doing the desugaring, and then store the result in a wrapper
object the kernel AST.  The wrapper object defers visit methods to the
object it wraps, so when the kernel objects are serialized to disk,
the wrapper disappears.

I also took the liberty of removing the code that inserts types
into the temporary variables and conditional expressions
introduced by desugaring.  I will add this in a later CL if it
proves to be necessary.

R=ahe@google.com, scheglov@google.com

Committed: https://github.com/dart-lang/sdk/commit/4abff2291b603d8f4ec95826b58f822fa1cc7fa8

[Paul Berry, 2017-06-08 22:39:34]

Description was changed from

==========
Rework type inference of assignments to index expressions.

The approach from the las CL (try to figure out the structure of the
assignment expression from the desugared result) turned out to be
unsustainably complex.  In this version we keep track of the structure
while doing the desugaring, and then store the result in a wrapper
object the kernel AST.  The wrapper object defers visit methods to the
object it wraps, so when the kernel objects are serialized to disk,
the wrapper disappears.
==========

to

==========
Rework type inference of assignments to index expressions.

The approach from the las CL (try to figure out the structure of the
assignment expression from the desugared result) turned out to be
unsustainably complex.  In this version we keep track of the structure
while doing the desugaring, and then store the result in a wrapper
object the kernel AST.  The wrapper object defers visit methods to the
object it wraps, so when the kernel objects are serialized to disk,
the wrapper disappears.

I also took the liberty of removing the code that inserts types
into the temporary variables and conditional expressions
introduced by desugaring.  I will add this in a later CL if it
proves to be necessary.
==========

[Paul Berry, 2017-06-08 22:40:25]

paulberry@google.com changed reviewers:
+ ahe@google.com, scheglov@google.com

[scheglov, 2017-06-09 00:44:07]

LGTM

[ahe, 2017-06-09 08:41:35]

lgtm

[Paul Berry, 2017-06-09 17:48:14]

Description was changed from

==========
Rework type inference of assignments to index expressions.

The approach from the las CL (try to figure out the structure of the
assignment expression from the desugared result) turned out to be
unsustainably complex.  In this version we keep track of the structure
while doing the desugaring, and then store the result in a wrapper
object the kernel AST.  The wrapper object defers visit methods to the
object it wraps, so when the kernel objects are serialized to disk,
the wrapper disappears.

I also took the liberty of removing the code that inserts types
into the temporary variables and conditional expressions
introduced by desugaring.  I will add this in a later CL if it
proves to be necessary.
==========

to

==========
Rework type inference of assignments to index expressions.

The approach from the las CL (try to figure out the structure of the
assignment expression from the desugared result) turned out to be
unsustainably complex.  In this version we keep track of the structure
while doing the desugaring, and then store the result in a wrapper
object the kernel AST.  The wrapper object defers visit methods to the
object it wraps, so when the kernel objects are serialized to disk,
the wrapper disappears.

I also took the liberty of removing the code that inserts types
into the temporary variables and conditional expressions
introduced by desugaring.  I will add this in a later CL if it
proves to be necessary.

R=ahe@google.com, scheglov@google.com

Committed:
https://github.com/dart-lang/sdk/commit/4abff2291b603d8f4ec95826b58f822fa1cc7fa8
==========

[Paul Berry, 2017-06-09 17:48:15]

Committed patchset #1 (id:1) manually as
4abff2291b603d8f4ec95826b58f822fa1cc7fa8 (presubmit successful).