[VM] Fix deserialization of arrays with type arguments in ApiMessageReader.

[VM] Fix deserialization of arrays with type arguments in ApiMessageReader.

A placeholder object must be created and registered via AddBackRef(...) *before*
any inner objects are deserialized otherwise NextAvailableObjectId() might
reuse current object id for an inner object with omitted object id leading
to inconsistent back references state.

Also handle kObjectType in ReadIndexedObject allowing it to deserialize things
like <Object>[...].

This bug was revealed by trying out to run VMService isolate in Kernel mode
with strong mode enabled leading to arrays that had no type arguments have
(inferred) type arguments.

R=kustermann@google.com
BUG=

Committed: https://github.com/dart-lang/sdk/commit/08d2841def85942f6bed713e7ca9390f46e901bd

[kustermann, 2017-08-25 09:03:43]

LGTM

[Vyacheslav Egorov (Google), 2017-08-25 09:51:26]

Description was changed from

==========
[VM] Fix deserialization of arrays with type arguments in ApiMessageReader.

A placeholder object must be created and registered via AddBackRef(...) *before*
any inner objects are deserialized otherwise NextAvailableObjectId() might
reuse current object id for an inner object with omitted object id leading
to inconsistent back references state.

Also handle kObjectType in ReadIndexedObject allowing it to deserialize things
like <Object>[...].

This bug was revealed by trying out to run VMService isolate in Kernel mode
with strong mode enabled leading to arrays that had no type arguments have
(inferred) type arguments.

R=kustermann@google.com
BUG=
==========

to

==========
[VM] Fix deserialization of arrays with type arguments in ApiMessageReader.

A placeholder object must be created and registered via AddBackRef(...) *before*
any inner objects are deserialized otherwise NextAvailableObjectId() might
reuse current object id for an inner object with omitted object id leading
to inconsistent back references state.

Also handle kObjectType in ReadIndexedObject allowing it to deserialize things
like <Object>[...].

This bug was revealed by trying out to run VMService isolate in Kernel mode
with strong mode enabled leading to arrays that had no type arguments have
(inferred) type arguments.

R=kustermann@google.com
BUG=

Committed:
https://github.com/dart-lang/sdk/commit/08d2841def85942f6bed713e7ca9390f46e901bd
==========

[Vyacheslav Egorov (Google), 2017-08-25 09:51:28]

Committed patchset #1 (id:1) manually as
08d2841def85942f6bed713e7ca9390f46e901bd (presubmit successful).