Fix check for empty type

R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/307453005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21538 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
MIPS: Convert String array index/length hash to BitField.

Port r21533 (736c779)

BUG=
R=plind44@gmail.com

Review URL: https://codereview.chromium.org/297233007

Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21539 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
MIPS64: Convert String array index/length hash to BitField.

Port r21539 (11d2da4)
Merge commit '11d2da48ff848928bc5ed32cd1652754e57b1b69' into mips64-gbl