Fix gyp_v8 to work with use_system_icu=1

If you want to use the system icu library, you'll need to use gyp_v8 (as
opposed to the standalone Makefiles)

BUG=v8:2475
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/19195003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15677 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Make optimizations for debug configurable with compile flag.

To turn on optimizations for debug when building standalone, a compiler flag can be used:

make optdebug=on

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/19164003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15678 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Disable compiled_transitions by default.

This was accidently re-enabled with r15674.

TBR=danno@chromium.org

Review URL: https://codereview.chromium.org/19229003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15679 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Revert r15649 and fix for loop dominator propagation in GVN.

BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/19233002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15680 ce2b1a6d-e550-0410-aec6-3dcde31c8c00