commit a316db995e6e4253664920652ed4e5a38b2caeba
author adamk <adamk@chromium.org> Wed Nov 04 16:06:18 2015
committer Commit bot <commit-bot@chromium.org> Wed Nov 04 16:06:38 2015
tree 1f3ffd1856300533b21d226888749c26c3b2e502
parent 19bad2a68c1a40de7db75a85f61ccc74c5e81eb8

[es6] Implement destructuring binding in try/catch

The approach is to desugar

  try { ... }
  catch ({x, y}) { ... }

into

  try { ... }
  catch (.catch) {
    let x = .catch.x;
    let y = .catch.y;
    ...
  }

using the PatternRewriter's normal facilities. This has the side benefit
of throwing the appropriate variable conflict errors for declarations
made inside the catch block.

No change is made to non-destructured cases, which will hopefully save
us some work if https://github.com/tc39/ecma262/issues/150 is adopted
in the spec.

There's one big problem with this patch, which is a lack of PreParser
support for the redeclaration errors. But it seems we're already lacking
good PreParser support for such errors, so I'm not sure that should
block this moving forward.

BUG=v8:811
LOG=y

Review URL: https://codereview.chromium.org/1417483014

Cr-Commit-Position: refs/heads/master@{#31797}