Remove pseudo-node from LoadLocalNode and replace it with a proper AST node.

Remove pseudo-node from LoadLocalNode and replace it with a proper AST node.

The newly introduces CommaNode denotes a sequence of two nodes, the result
is the value of the second child node.

There are only two places where the pseudo-node was used, and therefore
it does not warrant adding an extra member to all LoadLocalNode objects.

R=kmillikin@google.com

Committed: https://code.google.com/p/dart/source/detail?r=23243

[Kevin Millikin (Google), 2013-05-28 09:13:26]

LGTM, but could you support flat sequences of more than two children?  Pretty
please?

https://codereview.chromium.org/15935005/diff/1/runtime/vm/ast.h
File runtime/vm/ast.h (right):

https://codereview.chromium.org/15935005/diff/1/runtime/vm/ast.h#newcode188
runtime/vm/ast.h:188: CommaNode(intptr_t token_pos,
As discussed offline, I think that this node should allow a sequence of AstNode
children.  This is a case where the representation should allow flat sequences
(e.g., supporting cascades).

https://codereview.chromium.org/15935005/diff/1/runtime/vm/flow_graph_builder.cc
File runtime/vm/flow_graph_builder.cc (right):

https://codereview.chromium.org/15935005/diff/1/runtime/vm/flow_graph_builder...
runtime/vm/flow_graph_builder.cc:3146: EffectGraphVisitor
for_effect_first(owner(), temp_index());
Here and below: a loop over the children if you support more than two.

[Florian Schneider, 2013-05-28 09:22:35]

Yes. I'll add that functionality in a separate CL.

https://codereview.chromium.org/15935005/diff/1/runtime/vm/ast.h
File runtime/vm/ast.h (right):

https://codereview.chromium.org/15935005/diff/1/runtime/vm/ast.h#newcode188
runtime/vm/ast.h:188: CommaNode(intptr_t token_pos,
On 2013/05/28 09:13:26, kmillikin wrote:
> As discussed offline, I think that this node should allow a sequence of
AstNode
> children.  This is a case where the representation should allow flat sequences
> (e.g., supporting cascades).

Agree. I'll do that in a separate CL.

[Florian Schneider, 2013-05-28 09:30:49]

Committed patchset #1 manually as r23243 (presubmit successful).