MIPS: Add kExpectedFixedArrayInRegisterA2 message.

Port r19244 (08e0afd9)

BUG=
R=mvstanton@chromium.org, plind44@gmail.com

Review URL: https://codereview.chromium.org/159423003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19263 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Remove obsolete stack trace string in a message object.

The stack trace string is an ancient relic that is no longer being used.
We use the structured stack trace object instead.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/159013002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19264 ce2b1a6d-e550-0410-aec6-3dcde31c8c00