Fix several package spec bugs.

Fix several package spec bugs.

* The package spec's reference to the entrypoint package was pointing to
  the hosted cache rather than the package's directory. This was caused
  by the package graph's instance of the entrypoint package incorrectly
  pointing to the cache; the graph now re-uses `entrypoint.root`.

* The package spec didn't contain relative paths for relative path
  dependencies. This was being missed by our tests because the package
  spec parser was automatically converting all paths to absolute at
  parse-time.

Closes #1294

R=rnystrom@google.com

Committed: https://github.com/dart-lang/pub/commit/9cb2334b6c0c1a2be2ca0558b5aceb1f0a27216e

[Bob Nystrom, 2015-07-09 19:42:56]

lgtm

https://codereview.chromium.org/1228093003/diff/1/test/descriptor/packages.dart
File test/descriptor/packages.dart (right):

https://codereview.chromium.org/1228093003/diff/1/test/descriptor/packages.da...
test/descriptor/packages.dart:80: var base = "/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p";
Does this really need to be so long?

https://codereview.chromium.org/1228093003/diff/1/test/packages_file_test.dart
File test/packages_file_test.dart (right):

https://codereview.chromium.org/1228093003/diff/1/test/packages_file_test.dar...
test/packages_file_test.dart:95: "baz": "../local_baz"})]).validate();
Format this.

[nweiz, 2015-07-09 19:45:55]

Code review changes

[nweiz, 2015-07-09 19:46:05]

https://codereview.chromium.org/1228093003/diff/1/test/descriptor/packages.dart
File test/descriptor/packages.dart (right):

https://codereview.chromium.org/1228093003/diff/1/test/descriptor/packages.da...
test/descriptor/packages.dart:80: var base = "/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p";
On 2015/07/09 19:42:56, Bob Nystrom wrote:
> Does this really need to be so long?

Probably not in practice, but it doesn't cost much and I want to be *really
sure* that a long relative path isn't going to break it.

https://codereview.chromium.org/1228093003/diff/1/test/packages_file_test.dart
File test/packages_file_test.dart (right):

https://codereview.chromium.org/1228093003/diff/1/test/packages_file_test.dar...
test/packages_file_test.dart:95: "baz": "../local_baz"})]).validate();
On 2015/07/09 19:42:56, Bob Nystrom wrote:
> Format this.

Done.

[nweiz, 2015-07-09 19:46:14]

Committed patchset #2 (id:20001) manually as
9cb2334b6c0c1a2be2ca0558b5aceb1f0a27216e (presubmit successful).

[Lasse Reichstein Nielsen, 2015-07-13 07:15:37]

lrn@google.com changed reviewers:
+ lrn@google.com

[Lasse Reichstein Nielsen, 2015-07-13 07:15:37]

https://codereview.chromium.org/1228093003/diff/20001/test/descriptor/package...
File test/descriptor/packages.dart (right):

https://codereview.chromium.org/1228093003/diff/20001/test/descriptor/package...
test/descriptor/packages.dart:79: // "." due to sdk#23809.
sdk#23809 could be http://dartbug.com/23809 ?

[nweiz, 2015-07-13 20:03:44]

https://codereview.chromium.org/1228093003/diff/20001/test/descriptor/package...
File test/descriptor/packages.dart (right):

https://codereview.chromium.org/1228093003/diff/20001/test/descriptor/package...
test/descriptor/packages.dart:79: // "." due to sdk#23809.
On 2015/07/13 07:15:37, Lasse Reichstein Nielsen wrote:
> sdk#23809 could be http://dartbug.com/23809 ?

I'd rather use a more GitHub-like convention. This also means we can use the
same convention for issues in the SDK and in various other repos.

[Lasse Reichstein Nielsen, 2015-07-16 14:51:58]

https://codereview.chromium.org/1228093003/diff/20001/test/descriptor/package...
File test/descriptor/packages.dart (right):

https://codereview.chromium.org/1228093003/diff/20001/test/descriptor/package...
test/descriptor/packages.dart:79: // "." due to sdk#23809.
But it also means that there is no direct way for me to go to the error when
reading the code, where I could just cut-n-paste the link into a browser.