Implement yield* (delegating yield)

Implement yield* (delegating yield)

Ideally this would have been implemented via desugaring at parse-time,
but yield* is an expression, and its desugaring includes statements like
while and try/catch.  We'd have to have BlockExpression in the AST to
support that, and it's not worth it for this feature.

So instead we implement all of the logic in
FullCodeGenerator::VisitYield.  Delegating yield AST nodes now have a
try handler index, for the try/catch.  Otherwise the implementation is
straightforward.

R=rossberg@chromium.org
BUG=v8:2355
TEST=mjsunit/harmony/generators-iteration

Committed: 14669

[wingo, 2013-05-02 17:29:54]

Based on https://codereview.chromium.org/14031028/.  PTAL :)

[Michael Starzinger, 2013-05-07 10:19:31]

Andreas has agreed to take a look at this one. Thanks!

[rossberg, 2013-05-13 11:14:55]

https://codereview.chromium.org/14582007/diff/1/src/ia32/full-codegen-ia32.cc
File src/ia32/full-codegen-ia32.cc (right):

https://codereview.chromium.org/14582007/diff/1/src/ia32/full-codegen-ia32.cc...
src/ia32/full-codegen-ia32.cc:1936: // catch (e) { receiver = iter; f =
iter.throw; arg = e; }
...; goto l_call;

https://codereview.chromium.org/14582007/diff/1/src/ia32/full-codegen-ia32.cc...
src/ia32/full-codegen-ia32.cc:1941: __ mov(edx, Operand(esp, 3 * kPointerSize));
      // iter
Nit: Why not do this 2 lines earlier and then push edx?

https://codereview.chromium.org/14582007/diff/1/src/ia32/full-codegen-ia32.cc...
src/ia32/full-codegen-ia32.cc:1967: __ mov(edx, Operand(esp, 3 * kPointerSize));
      // iter
Nit: same here

https://codereview.chromium.org/14582007/diff/1/src/ia32/full-codegen-ia32.cc...
src/ia32/full-codegen-ia32.cc:1970: CallIC(send_ic);                            
      // iter.send in rax
s/rax/eax/

https://codereview.chromium.org/14582007/diff/1/test/mjsunit/harmony/generato...
File test/mjsunit/harmony/generators-iteration.js (right):

https://codereview.chromium.org/14582007/diff/1/test/mjsunit/harmony/generato...
test/mjsunit/harmony/generators-iteration.js:375: // same as *** above with
delegate
Would be cool if all these Test functions were factored such that they take a
generator as argument and then run all tests with that. Then you could simply
invoke it twice with both the flat and the delegating generator (and potentially
other variations) and avoid code duplication.

[wingo, 2013-05-14 14:02:07]

Updated patch fixes nits and really puts yield* through the wringer.  Please
take a look :-)

[rossberg, 2013-05-14 14:22:53]

lgtm

[wingo, 2013-05-14 16:27:07]

Committed patchset #2 manually as r14669 (presubmit successful).