MIPS: Clean up name distinction between Keyed ICs and Element Handlers

Port r22679 (c6e3041b)

BUG=
R=paul.lind@imgtec.com

Review URL: https://codereview.chromium.org/430593002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22685 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
MIPS: Only generate a single normal IC per kind per slow-mode map.

Port r22680 (8b865409)

BUG=
R=paul.lind@imgtec.com

Review URL: https://codereview.chromium.org/426073002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22686 ce2b1a6d-e550-0410-aec6-3dcde31c8c00