ClusterFuzz test is triggering assertions for dead code. This fix issues
HDeoptimize instruction when it finds out that the compare instruction
is dead (because of previous checks).

R=yangguo@chromium.org
BUG=359491
LOG=N

Review URL: https://codereview.chromium.org/228883005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20620 ce2b1a6d-e550-0410-aec6-3dcde31c8c00