Add os.chdir and os.setenv to d8. Move system() to os.system().

Add os.chdir and os.setenv to d8.  Move system() to os.system().
Protect os.chdir, os.setenv, os.system against string conversion
failures.  Add comment about the issue to include/v8.h.

Committed: http://code.google.com/p/v8/source/detail?r=1644

[Mads Ager (chromium), 2009-03-30 09:18:12]

LGTM

Consider adding explicit null checks before calling the library routines?

http://codereview.chromium.org/57005/diff/1/3
File src/d8-posix.cc (right):

http://codereview.chromium.org/57005/diff/1/3#newcode510
Line 510: if (chdir(*directory) != 0) {
How does chdir deal with NULL pointers?

http://codereview.chromium.org/57005/diff/1/4
File src/d8.cc (right):

http://codereview.chromium.org/57005/diff/1/4#newcode173
Line 173: setenv(*var, *value, 1);
How does setenv feel about NULL pointers?  The string conversions might have
failed in which case the *var and *value will be NULL.

http://codereview.chromium.org/57005/diff/1/5
File src/d8.h (right):

http://codereview.chromium.org/57005/diff/1/5#newcode148
Line 148: // exception/ on error.
exception/ -> exception

[Mads Ager (chromium), 2009-03-31 05:54:56]

LGTM