IDL: Add error handlings to avoid infinite loops

IDL: Add error handlings to avoid infinite loops

The IDL parser lacks some error propagation rules, which cause
infinite loops when an IDL file contains syntax errors. This
CL fixes following two cases:
(1) Missing arguments:
  interface I {
    void foo(DOMString arg, );
  };
(2) Unexpected "attribute" in dictionary
  dictionary D {
    attribute DOMString member = "";
  };

BUG=435794
Committed: https://crrev.com/d54ddee89897d16b1611a7dc80c8eb4aed81b422
Cr-Commit-Position: refs/heads/master@{#306049}

[bashi, 2014-11-28 01:19:13]

bashi@chromium.org changed reviewers:
+ haraken@chromium.org, noelallen@chromium.org

[bashi, 2014-11-28 01:19:14]

PTAL?

[haraken, 2014-11-28 01:36:44]

LGTM

[bashi, 2014-11-28 05:18:14]

The CQ bit was checked by bashi@chromium.org

[commit-bot: I haz the power, 2014-11-28 05:19:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/761223002/1

[commit-bot: I haz the power, 2014-11-28 05:58:10]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-11-28 05:58:57]

Patchset 1 (id:??) landed as
https://crrev.com/d54ddee89897d16b1611a7dc80c8eb4aed81b422
Cr-Commit-Position: refs/heads/master@{#306049}