Move code flushing support into shared visitor. (issue 11028016)

[mstar...@chromium.org]

Reviewers: ulan,

Description:
Move code flushing support into shared visitor.

This is a first step towards incremental code flushing. The code
flushing support is now shared between full and incremental marking.
The code flusher itself is not yet activated in incremental mode and
will require some additional adaptations.

R=ul...@chromium.org


Please review this at https://codereview.chromium.org/11028016/

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

Affected files:
M src/incremental-marking.cc
M src/mark-compact.h
M src/mark-compact.cc
M src/objects-visiting-inl.h
M src/objects-visiting.h