Resolve references to "this" the same way as normal variables

Resolve references to "this" the same way as normal variables

Make the parser handle references to "this" as unresolved variables, so the
same logic as for the rest of function parameters is used for the receiver.
Minor additions to the code generation handle copying the receiver to the
context, along with the rest of the function parameters.

Based on work by Adrian Perez de Castro <aperez@igalia.com>;.

This is a reapplication of https://codereview.chromium.org/1130733003.

R=rossberg@chromium.org
BUG=v8:2700
LOG=N

Committed: https://crrev.com/bd56d279b612f92d2d1d25f92d32fe7f42a455ca
Cr-Commit-Position: refs/heads/master@{#28340}

[wingo, 2015-05-11 10:22:59]

PTAL.  Patchset 1 is the original "this" scoping patch as previously applied. 
Patchset 2 fixes a case in which "this" would be given DYNAMIC_LOCAL lookup. 
Similarly to the previous "with" case that was only caught by the mozilla tests,
this one was caught with the following standalone case:

  var globalEval = eval;
  globalEval("this; eval('42')");

The "this" was getting marked as DYNAMIC_LOCAL because maybe the eval could
interpose a binding.  However lookup of "this" in script scope won't always
work, because "this" might not be context-allocated in the script.  That should
be fixed for other reasons, but it turns out that it's always possible to
statically resolve "this", which is the change that this patchset makes.

Oddly our mjsunit tests didn't catch this one because something about the
mjsunit.js file itself causes "this" to be context-allocated :/  For that reason
I marked this test as to be run without the harness, and adapted the test-runner
script appropriately.

[rossberg, 2015-05-11 10:44:56]

lgtm

[wingo, 2015-05-11 11:25:16]

The CQ bit was checked by wingo@igalia.com

[commit-bot: I haz the power, 2015-05-11 11:25:26]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1136073002/20001

[commit-bot: I haz the power, 2015-05-11 11:49:54]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-05-11 11:50:08]

Patchset 2 (id:??) landed as
https://crrev.com/bd56d279b612f92d2d1d25f92d32fe7f42a455ca
Cr-Commit-Position: refs/heads/master@{#28340}