Improve memory usage of receiver type feedback.

Improve memory usage of receiver type feedback.

Some AST nodes (Property, Call, etc.) store either a list of receiver
types or a monomorphic receiver type. This patch merges the two fields
using a small pointer list. GetMonomorphicReceiverType() is now a
purely convenience function returning the first and only recorded
type.

This saves about 500K (of about 39M) on average when compiling V8
benchmark as measured by a simple patch adding a zone allocation
counter (https://gist.github.com/1149397).

R=kmillikin@chromium.org

Committed: http://code.google.com/p/v8/source/detail?r=8993

[fschneider, 2011-08-22 13:38:06]

LGTM.

http://codereview.chromium.org/7655017/diff/2001/src/ast.h
File src/ast.h (right):

http://codereview.chromium.org/7655017/diff/2001/src/ast.h#newcode216
src/ast.h:216: void Reserve(int capacty) { list_.Reserve(capacty); }
capacty -> capacity