Load/Store cannot handle double representation.

Assert that the representation for Load/Store in the X64 MacroAssembler
is never Double. Also add missing test case for the Load/Store macros.

TEST=cctest/test-macro-assembler-x64
R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/25990002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17135 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Unify and fix checkers for duplicate object literal properties.

R=ulan@chromium.org
TEST=preparser/duplicate-property,mjsunit/regress/regress-parse-object-literal

Review URL: https://codereview.chromium.org/26375004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17136 ce2b1a6d-e550-0410-aec6-3dcde31c8c00