Add read-only environment variable access.

Add read-only environment variable access.

Map<String, String> env = new Platform().environment();

Unfortunately, this is a bit hard to test at this point. I
will move on to implement support for providing an environment
to processes that are started. At that point we can test it
properly.

Another follow-up change will be to remove the instantiation
for Platform. I would like this to be just

Map<String, String> env = Platform.environment();

R=sgjesse@google.com
BUG=dartbug.com/752
TEST=

Committed: https://code.google.com/p/dart/source/detail?r=6646

[Søren Gjesse, 2012-04-17 16:10:47]

lgtm

Not that bad after all.

http://codereview.chromium.org/10112002/diff/3001/runtime/bin/platform_linux.cc
File runtime/bin/platform_linux.cc (right):

http://codereview.chromium.org/10112002/diff/3001/runtime/bin/platform_linux....
runtime/bin/platform_linux.cc:45: intptr_t i = 0;
Why add i? Maybe just use *count instead.

[Mads Ager (google), 2012-04-17 16:20:14]

http://codereview.chromium.org/10112002/diff/3001/runtime/bin/platform_linux.cc
File runtime/bin/platform_linux.cc (right):

http://codereview.chromium.org/10112002/diff/3001/runtime/bin/platform_linux....
runtime/bin/platform_linux.cc:45: intptr_t i = 0;
On 2012/04/17 16:10:47, Søren Gjesse wrote:
> Why add i? Maybe just use *count instead.

I wanted to have on clear assignment to count. Also, I found it easier to read
because of the occurrences of 'i' below as well.