Fix spread array inside array literal

Fix spread array inside array literal

During parsing, we now keep track of the first spread seen in an array
literal (if any), and make use of that information when creating the
FixedArray backing store representing the constant elements for array
literal materialization.

The old code tried to do this by setting the generated JSArray's length
in ArrayLiteral::BuildConstantElements(), but that Array length is never
read by the rest of the literal materialization code (it always uses
the length of the FixedArray backing store).

BUG=v8:4298
LOG=n

Committed: https://crrev.com/24e982816f75cb91b96b6c3aafbc6ab741afd118
Cr-Commit-Position: refs/heads/master@{#29684}

[adamk, 2015-07-14 05:32:40]

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

[commit-bot: I haz the power, 2015-07-14 05:32:50]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1225223004/1

[commit-bot: I haz the power, 2015-07-14 05:36:24]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-07-14 05:36:26]

Dry run: Try jobs failed on following builders:
  v8_presubmit on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_presubmit/builds/4163)

[caitp (gmail), 2015-07-14 05:49:02]

caitpotter88@gmail.com changed reviewers:
+ caitpotter88@gmail.com

[caitp (gmail), 2015-07-14 05:49:03]

https://codereview.chromium.org/1225223004/diff/1/src/ast.cc
File src/ast.cc (right):

https://codereview.chromium.org/1225223004/diff/1/src/ast.cc#newcode514
src/ast.cc:514: constants_length = i;
Looks like you just need a `break` here to make this work

[caitp (gmail), 2015-07-14 05:49:53]

https://codereview.chromium.org/1225223004/diff/1/src/ast.cc
File src/ast.cc (right):

https://codereview.chromium.org/1225223004/diff/1/src/ast.cc#newcode514
src/ast.cc:514: constants_length = i;
On 2015/07/14 05:49:03, caitp wrote:
> Looks like you just need a `break` here to make this work

Otherwise if there are multiple spread elements, it will make the constant
length too high

[caitp (gmail), 2015-07-14 05:55:13]

On 2015/07/14 05:49:53, caitp wrote:
> https://codereview.chromium.org/1225223004/diff/1/src/ast.cc
> File src/ast.cc (right):
> 
> https://codereview.chromium.org/1225223004/diff/1/src/ast.cc#newcode514
> src/ast.cc:514: constants_length = i;
> On 2015/07/14 05:49:03, caitp wrote:
> > Looks like you just need a `break` here to make this work
> 
> Otherwise if there are multiple spread elements, it will make the constant
> length too high

looks good to me with the little fixup

[adamk, 2015-07-14 16:04:56]

https://codereview.chromium.org/1225223004/diff/1/src/ast.cc
File src/ast.cc (right):

https://codereview.chromium.org/1225223004/diff/1/src/ast.cc#newcode514
src/ast.cc:514: constants_length = i;
On 2015/07/14 05:49:53, caitp wrote:
> On 2015/07/14 05:49:03, caitp wrote:
> > Looks like you just need a `break` here to make this work
> 
> Otherwise if there are multiple spread elements, it will make the constant
> length too high

Oops, indeed, I refactored this from a different approach below.

[adamk, 2015-07-14 18:53:57]

adamk@chromium.org changed reviewers:
+ rossberg@chromium.org

[adamk, 2015-07-14 18:53:57]

Okay, this is ready for review. Different approach this time, which avoids extra
looping through the array values by storing the first spread seen in the AST. I
worried that the first approach could be bad for very large array literals.

[rossberg, 2015-07-15 08:51:36]

lgtm

[adamk, 2015-07-15 15:13:58]

The CQ bit was checked by adamk@chromium.org

[commit-bot: I haz the power, 2015-07-15 15:14:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1225223004/80001

[commit-bot: I haz the power, 2015-07-15 15:16:13]

Committed patchset #5 (id:80001)

[commit-bot: I haz the power, 2015-07-15 15:16:20]

Patchset 5 (id:??) landed as
https://crrev.com/24e982816f75cb91b96b6c3aafbc6ab741afd118
Cr-Commit-Position: refs/heads/master@{#29684}