Remove bash-specific syntax from traceurc. (trivial patch)

Remove bash-specific syntax from traceurc.

${parameter:offset:length} and 'exit -1' are a bash-specific features.
${parameter#prefix_to_remove} and 'exit 1' are passable replacements this case.

This is a problem on Debian-based systems, or any system where /bin/sh is not a
symlink to /bin/bash. Syntax tested with bash, dash and Busybox ash, and should
work with BSD sh, according to the man page.

BUG=http://code.google.com/p/traceur-compiler/issues/detail?id=111

[usrbincc, 2012-10-22 22:19:05]

This is one of two small usability patches.

This one allows traceurc to run unmodified on Debian-based systems.

[arv, 2012-10-23 13:36:29]

LGTM

Does build/build have any issues?

[arv, 2012-10-23 14:34:12]

Committed as

http://code.google.com/p/traceur-compiler/source/detail?r=1fb3ebaffe063be92c1...

[usrbincc, 2012-10-23 20:23:38]

Oops, I didn't realize the typos until I saw the commit.

It was originally:
  x is a bash-specific feature, which can be replaced with x2.
  y is also a bash-specific feature, which can be replaced with y2.

but I didn't finish editing everything when rearranging.

I'll have to be especially careful about commit messages from now on.
Git is forever, and all that.

In the future, any committers are given full rein to correct my more
egregious English and logic errors. The subtle ones, I'll call
"personality". <-- like that.

[usrbincc, 2012-11-02 17:03:44]

On 2012/10/23 13:36:29, arv-chromium wrote:
> LGTM
>
> Does build/build have any issues?
I missed this question last time. For the record, I did not notice any
/bin/sh compatibility issues running build/build