Several changes are included here:

1. Each resolution callback references shared data indicating whether
it has already been resolved or not, as described in 25.4.1.3
http://tc39.github.io/ecma262/#sec-createresolvingfunctions.
Previously this was handled exclusively by the Promise's status,
which does not work correctly with the current chaining behaviour.

2. During fulfillment, When a Promise is resolved with a thenable, the
spec chains the promises together by invoking the thenable's `then`
function with the original Promise's resolve and reject methods (per
section 25.4.2.2, or
http://tc39.github.io/ecma262/#sec-promiseresolvethenablejob, on the
next tick, regardless of whether or not there are pending tasks.

3. Adds a spec compliance fix to ensure that the Promise constructor
is only loaded once when `then()` is called, solving v8:4539 as well.
This involves refactoring PromiseChain to accept a constructor
argument. PromiseChain/PromiseDeferred will hopefully be removed soon,
simplifying the process.

BUG=v8:4162, v8:4539, v8:3237
LOG=N
R=rossberg@chromium.org, littledan@chromium.org, adamk@chromium.org

Review URL: https://codereview.chromium.org/1394463003

Cr-Commit-Position: refs/heads/master@{#32046}