Change the overly-general class named Node to the more specific...

[kmil...@chromium.org]

Reviewers: Kasper Lund,

Description:
Change the overly-general class named Node to the more specific
AstNode in case we ever want to have some other kind of node.

Split the NODE_LIST macro-generating macro so that we can iterate
concrete subclasses of Statement and concrete subclasses of Expression
separately.

Please review this at http://codereview.chromium.org/159632

SVN Base: http://v8.googlecode.com/svn/branches/bleeding_edge/

Affected files:
M src/arm/codegen-arm.h
M src/ast.h
M src/codegen.cc
M src/ia32/codegen-ia32.h
M src/parser.cc
M src/prettyprinter.h
M src/prettyprinter.cc
M src/usage-analyzer.cc
M src/x64/codegen-x64.h

[kas...@chromium.org]

LGTM.

http://codereview.chromium.org/159632