[turbofan] Properly delete nodes in the GraphReducer.

This is required to enable a value numbering reducer, which needs to be
able to recognize "dead nodes".

TEST=compiler-unittests,cctest
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/541643002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23675 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Add missing -Wno-missing-field-initializer flag to standalone.gypi.

Chrome uses -Wno-missing-field-initializers when building V8, so we
should better use that as well. It silences warnings generated for the
GTest port files.

BUG=v8:3518
LOG=n
R=jochen@chromium.org

Review URL: https://codereview.chromium.org/535283006

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23676 ce2b1a6d-e550-0410-aec6-3dcde31c8c00