gn format: Fix and enable a few more tests

gn format: Fix and enable a few more tests

This follows on https://codereview.chromium.org/748863003/ and takes
care of a few edge cases that were causing ugly output.

After this CL, I'm happy enough with the output of reformatting all
(https://codereview.chromium.org/704363002) to say it's generally
useful.

R=brettw@chromium.org
BUG=348474
Committed: https://crrev.com/25919ddcafc0615936c49bebd0b34a6976cd26d7
Cr-Commit-Position: refs/heads/master@{#305898}

[brettw, 2014-11-26 18:32:07]

lgtm

https://codereview.chromium.org/756413002/diff/120001/tools/gn/format_test_da...
File tools/gn/format_test_data/026.golden (right):

https://codereview.chromium.org/756413002/diff/120001/tools/gn/format_test_da...
tools/gn/format_test_data/026.golden:2:
rebase_path("$target_gen_dir/experimental-libraries.cc", root_build_dir),
This is interesting. I was going to say this is wrong, but actually might be a
better way to format this.

[scottmg, 2014-11-26 18:39:54]

https://codereview.chromium.org/756413002/diff/120001/tools/gn/format_test_da...
File tools/gn/format_test_data/026.golden (right):

https://codereview.chromium.org/756413002/diff/120001/tools/gn/format_test_da...
tools/gn/format_test_data/026.golden:2:
rebase_path("$target_gen_dir/experimental-libraries.cc", root_build_dir),
On 2014/11/26 18:32:07, brettw wrote:
> This is interesting. I was going to say this is wrong, but actually might be a
> better way to format this.

Yeah, the special formatting for lists is a bit weird. It's special cased
because 

  sources = [
    "a",
    "b",
  ]

feels nicer than indented, but there's an indent on continuations in general so
the extra indent happens when there's a plus or something. i felt like it was ok
because it was a cue that there was something hiding at the end.

in some cases rewriting 

  args = [ some_long_multiline_thing ] + something_else

would probably be better written as

  args = [ some_long_multiline_thing ]
  args += something_else

anyway which would remove the extra indent.

there's an example that i'll probably do that for here:
https://codereview.chromium.org/704363002/diff/140001/BUILD.gn

[scottmg, 2014-11-26 21:04:09]

The CQ bit was checked by scottmg@chromium.org

[commit-bot: I haz the power, 2014-11-26 21:05:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/756413002/180001

[scottmg, 2014-11-26 21:32:41]

The CQ bit was checked by scottmg@chromium.org

[commit-bot: I haz the power, 2014-11-26 21:33:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/756413002/200001

[commit-bot: I haz the power, 2014-11-26 22:13:12]

Committed patchset #11 (id:200001)

[commit-bot: I haz the power, 2014-11-26 22:13:56]

Patchset 11 (id:??) landed as
https://crrev.com/25919ddcafc0615936c49bebd0b34a6976cd26d7
Cr-Commit-Position: refs/heads/master@{#305898}