Merged r19536 into 3.24 branch.

Don't eliminate loads with incompatible types or representations.

BUG=346343
LOG=N
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/181403002

git-svn-id: https://v8.googlecode.com/svn/branches/3.24@19557 ce2b1a6d-e550-0410-aec6-3dcde31c8c00