[destructuring] Grand for statement parsing unification.

[destructuring] Grand for statement parsing unification.

Also support patterns in ``for (var p in/of ...)``

This CL extends the rewriting we used to do for ``for (let p in/of...)`` to
``for (var p in/of ...)``. For all for..in/of loop declaring variable,
we rewrite
   for (var/let/const pattern in/of e) b
into
   for (x' in/of e) { var/let/const pattern = e; b }

This adds a small complication for debugger: for a statement
   for (var v in/of e) ...
we used to have
   var v;
   for (v in/of e) ...
and there was a separate breakpoint on ``var v`` line.
This breakpoint is actually useless since it is immediately followed by
a breakpoint on evaluation of ``e``, so this CL removes that breakpoint
location.

Similiraly, for let, it used to be that
  for (let v in/of e) ...
became
  for (x' in/of e) { let v; v  = x'; ... }
``let v``generetaed a useless breakpoint (with the location at the
loop's head. This CL removes that breakpoint as well.

R=arv@chromium.org,rossberg@chromium.org
BUG=v8:811
LOG=N

Committed: https://crrev.com/7ffdb5194d51a5813f9474d2453859c376223b18
Cr-Commit-Position: refs/heads/master@{#28565}

[Dmitry Lomov (no reviews), 2015-05-21 16:00:04]

The CQ bit was checked by dslomov@chromium.org to run a CQ dry run

[Dmitry Lomov (no reviews), 2015-05-21 16:00:14]

PTAL

[commit-bot: I haz the power, 2015-05-21 16:00:38]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1149043005/1

[arv (Not doing code reviews), 2015-05-21 16:37:01]

LGTM

https://codereview.chromium.org/1149043005/diff/1/test/mjsunit/harmony/destru...
File test/mjsunit/harmony/destructuring.js (right):

https://codereview.chromium.org/1149043005/diff/1/test/mjsunit/harmony/destru...
test/mjsunit/harmony/destructuring.js:680: var o = { 'a1':1, 'b2':2 };
var o = {__proto__: null, ...};

[Dmitry Lomov (no reviews), 2015-05-21 17:07:34]

Landing

https://codereview.chromium.org/1149043005/diff/1/test/mjsunit/harmony/destru...
File test/mjsunit/harmony/destructuring.js (right):

https://codereview.chromium.org/1149043005/diff/1/test/mjsunit/harmony/destru...
test/mjsunit/harmony/destructuring.js:680: var o = { 'a1':1, 'b2':2 };
On 2015/05/21 16:37:01, arv wrote:
> var o = {__proto__: null, ...};

Done.

[Dmitry Lomov (no reviews), 2015-05-21 17:07:44]

The CQ bit was checked by dslomov@chromium.org

[Dmitry Lomov (no reviews), 2015-05-21 17:07:44]

The patchset sent to the CQ was uploaded after l-g-t-m from arv@chromium.org
Link to the patchset: https://codereview.chromium.org/1149043005/#ps20001
(title: "Rebase   feedback")

[commit-bot: I haz the power, 2015-05-21 17:08:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1149043005/20001

[rossberg, 2015-05-21 17:18:04]

https://codereview.chromium.org/1149043005/diff/1/src/parser.cc
File src/parser.cc (right):

https://codereview.chromium.org/1149043005/diff/1/src/parser.cc#newcode3461
src/parser.cc:3461: // special case for legacy for (var/const x =.... in)
Does this actually work with const? You are doing a regular ASSIGN below.

https://codereview.chromium.org/1149043005/diff/1/src/parser.cc#newcode3464
src/parser.cc:3464: parsing_result.declarations[0].initializer != nullptr) {
Don't you need to also check that the LHS is a simple variable?

[Dmitry Lomov (no reviews), 2015-05-21 17:22:01]

https://codereview.chromium.org/1149043005/diff/1/src/parser.cc
File src/parser.cc (right):

https://codereview.chromium.org/1149043005/diff/1/src/parser.cc#newcode3461
src/parser.cc:3461: // special case for legacy for (var/const x =.... in)
On 2015/05/21 17:18:04, rossberg wrote:
> Does this actually work with const? You are doing a regular ASSIGN below.

It should only work for legacy const and it does (we have tests)

https://codereview.chromium.org/1149043005/diff/1/src/parser.cc#newcode3464
src/parser.cc:3464: parsing_result.declarations[0].initializer != nullptr) {
On 2015/05/21 17:18:04, rossberg wrote:
> Don't you need to also check that the LHS is a simple variable?

No this is done in the parser (see tests in test-parsing.cc)

[commit-bot: I haz the power, 2015-05-21 17:47:14]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-05-21 17:47:22]

Patchset 2 (id:??) landed as
https://crrev.com/7ffdb5194d51a5813f9474d2453859c376223b18
Cr-Commit-Position: refs/heads/master@{#28565}