Syntax and subtyping for strong dart

Syntax and subtyping for strong dart.  Initial pass on a core calculus for exploring and defining the key ideas underlying the strong dart type system.  This CL contains the initial latex setup, a proposed base syntax to start from, and the definition of subtyping.

BUG=
R=jmesserly@google.com, vsm@google.com

Committed: https://github.com/dart-lang/dev_compiler/commit/c350478a0c352ccf2fafd1683befa083afcc772c

[Leaf, 2015-06-25 00:27:31]

leafp@google.com changed reviewers:
+ jmesserly@google.com, vsm@google.com

[Leaf, 2015-06-25 00:29:50]

This is just an initial checkin to get things rolling.  The intention is that
this calculus include only the core things to keep it interesting, but if you
think there are aspects that I'm leaving out that are important to capture
please let me know.

Not sure if we want to check in the pdf or not?  Seems useful so people don't
have to build to reference it.

[Jennifer Messerly, 2015-06-25 15:32:47]

On 2015/06/25 00:29:50, Leaf wrote:
> This is just an initial checkin to get things rolling.  The intention is that
> this calculus include only the core things to keep it interesting, but if you
> think there are aspects that I'm leaving out that are important to capture
> please let me know.
> 
> Not sure if we want to check in the pdf or not?  Seems useful so people don't
> have to build to reference it.

I think the normal way to host a PDF would be to commit it to gh-pages:
https://pages.github.com/
(relevant question:
http://webapps.stackexchange.com/questions/48061/can-i-trick-github-into-disp...)

[vsm, 2015-06-25 15:55:37]

lgtm

[Jennifer Messerly, 2015-06-25 16:02:17]

FYI: http://dart-lang.github.io/dev_compiler/strong-dart.pdf
branch https://github.com/dart-lang/dev_compiler/tree/gh-pages

also, LGTM

[Leaf, 2015-06-25 20:17:06]

Committed patchset #1 (id:1) manually as
c350478a0c352ccf2fafd1683befa083afcc772c (presubmit successful).