Introduces "--initializing-formal-access".

Introduces "--initializing-formal-access".

This CL adjusts the treatment of initializing formals, such that they
can be used in initializers and in constructor bodies. E.g., `x` can be
used as in `C(this.x) : y = x { var z = x + 2; }`.

It hides the new feature under the option '--initializing-formal-access'
which is used in the test 'initializing_formal_access_test.dart'.

It also adds an `example` test to `MessageKind.DUPLICATE_DEFINITION` to
verify that name clashes among initializing formals and other
parameters are detected (which was previously not the case).

Finally, it fixes a typo in a comment, `InitializingFormalParameter` ->
`InitializingFormalElement`.

R=johnniwinther@google.com

Committed: https://github.com/dart-lang/sdk/commit/b80a73775cb1ba2539667a067ce608485cc136b7

[eernst, 2016-05-31 09:52:28]

eernst@google.com changed reviewers:
+ johnniwinther@google.com

[eernst, 2016-05-31 09:52:28]

Small feature enhancement: Allow for access to initializing formals, e.g., using
`x` as in `C(this.x) : y = x`.

[Johnni Winther, 2016-05-31 10:37:52]

lgtm

[eernst, 2016-05-31 13:08:40]

PTAL: Eliminated overriding methods `isParameter` and `isInstanceMember` in
`InitializingFormalElementX`, such that it avoids breaking the intended
semantics of those methods. Added checks for `isInitializingFormal` elsewhere to
compensate for that. All tests now succeeding.

[Johnni Winther, 2016-05-31 13:23:10]

lgtm

[eernst, 2016-05-31 13:39:14]

Description was changed from

==========
Introduces "--initializing-formal-access".

This CL adjusts the treatment of initializing formals, such that they
can be used in initializers and in constructor bodies. E.g., `x` can be
used as in `C(this.x) : y = x { var z = x + 2; }`.

It hides the new feature under the option '--initializing-formal-access'
which is used in the test 'initializing_formal_access_test.dart'.

It also adds an `example` test to `MessageKind.DUPLICATE_DEFINITION` to
verify that name clashes among initializing formals and other
parameters are detected (which was previously not the case).

Finally, it fixes a typo in a comment, `InitializingFormalParameter` ->
`InitializingFormalElement`.
==========

to

==========
Introduces "--initializing-formal-access".

This CL adjusts the treatment of initializing formals, such that they
can be used in initializers and in constructor bodies. E.g., `x` can be
used as in `C(this.x) : y = x { var z = x + 2; }`.

It hides the new feature under the option '--initializing-formal-access'
which is used in the test 'initializing_formal_access_test.dart'.

It also adds an `example` test to `MessageKind.DUPLICATE_DEFINITION` to
verify that name clashes among initializing formals and other
parameters are detected (which was previously not the case).

Finally, it fixes a typo in a comment, `InitializingFormalParameter` ->
`InitializingFormalElement`.

R=johnniwinther@google.com

Committed:
https://github.com/dart-lang/sdk/commit/b80a73775cb1ba2539667a067ce608485cc136b7
==========

[eernst, 2016-05-31 13:39:15]

Committed patchset #3 (id:40001) manually as
b80a73775cb1ba2539667a067ce608485cc136b7 (presubmit successful).