Bug 957688 - Make ComputeStackString pass a principal and remove checkAccess call. r=mrbkap

Now that we have the principal-based filtering for stack walking, we can do this.
This isn't technically equivalent to the old behavior, since a stack that goes:

A -> B -> A

would previous have only seen the second set of |A| frames, whereas now we'd
see both sets. But this seems strictly better (also, it doesn't happen on the
web).

As noted, I've filed a bug for making this context- and saveFrameChain-agnostic.
Bug 957688 - Remove JS_CheckAccess. r=mrbkap

But how will we call from Gecko into the JS engine to query CAPS via a callback?
Bug 957688 - Remove side-effect-free calls to js::CheckAccess. r=mrbkap

js::CheckAccess has all sorts of crazy side-effects on its parameters. Luckily,
they mostly happen on dead values.

We have to alter a jit-test that previously threw, and doesn't anymore. I have
confirmed that the reason for throwing was not the security check itself, but
rather the lookupGeneric call that happens inside js::CheckAccess, which ends
up throwing 'undefined is not a function'. It seems like this is just an issue
of calling lookupGeneric when we shouldn't, and that the correct behavior here
is not to throw.
Bug 957688 - Remove side-effect-y call to js::CheckAccess, and remove js::CheckAccess itself. r=mrbkap

Thankfully, this case was only taking the JSACC_PROTO, which is significantly
simpler than the alternative.
Bug 957688 - Remove checkObjectAccess security callback. r=mrbkap

There's no need for the JS shell stuff either, since vm/Runtime.cpp already
sets up NullSecurityCallbacks by default.
Bug 957688 - Remove checkAccess nsIXPCScriptable hook. r=mrbkap
Bug 957688 - Remove checkaccess junk from the XBL compilation scope. r=mrbkap

I have no idea what this is supposed to be doing, given that the compilation
scope doesn't run script. We should make sure this is reviewed by someone
who remembers why this was written.
Bug 957688 - Kill off checkAccess. r=mrbkap
Bug 957688 - Remove nsIScriptSecurityManager::CheckPropertyAccess. r=mrbkap
Bug 957688 - Remove nsIXPCSecurityManager::CanAccess and nsScriptSecurityManager::CheckPropertyAccessImpl. r=mrbkap

\o/