src: harden SlicedString::ToString

Add some extra checks to make sure we won't crash when stringifying a
(possibly corrupted) SlicedString.

PR-URL: nodejs#332
Reviewed-By: Colin Ihrig <[email protected]>

release: v2.2.0

Notable Changes:

  - Teach llnode how to print Symbol properties names

Commits:

  - [fdb49b8] doc: fix typo in README.md (hardfist)
  - [51bf1f6] src: fix formatting of context address within JSFunction
    (Matheus Marchini)
  - [a36611f] test: move workqueue tests to correct folder (Matheus
    Marchini)
  - [0c1e3ae] src: make source list -l flag optional (Matheus Marchini)
  - [a295239] src: refactor JSError stringifier (Matheus Marchini)
  - [9f3dce3] build: add coverage for javascript code (Matheus Marchini)
  - [43edf43] build: add support to gcov and codecov (Matheus Marchini)
  - [59b65c4] build: add support for Android Termux build (James R.
    Gambale, Jr)
  - [e30beba] src: teach llnode how to print Symbol properties names
    (Matheus Marchini)
  - [388605f] src: fix performance regression (Matheus Marchini)
  - [dbd95d7] build: load lldb symbols at runtime (Dane Springmeyer)
  - [c17d0d1] src: fix build on older compilers (gcc 4.8) (Matheus
    Marchini)
  - [c851b9a] src: introduce Printer class (Matheus Marchini)

PR-URL: nodejs#269
Reviewed-By: Joyee Cheung <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>

2.1.0

Notable Changes:

  * src: colorize output for findjsinstances
  * src: option to limit output of `findjsinstances`
  * src: print stack for error objects

PR-URL: nodejs#248
Reviewed-By: Joyee Cheung <[email protected]>

2.0.0

PR-URL: nodejs#231
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Joyee Cheung <[email protected]>

2.0.0

PR-URL: nodejs#231
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Joyee Cheung <[email protected]>

1.7.1

1.7.0

v1.6.3

PR-URL: nodejs#163
Fixes: nodejs#161
Reviewed-By: Colin Ihrig <[email protected]>

1.6.2

1.6.1