Changes to fix new warnings introduced by better type inferrencing of Array.prototype methods

Tested:
yes

R=eparker
DELTA=9 (0 added, 0 deleted, 9 changed)


Revision created by MOE tool push_codebase.
MOE_MIGRATION=6133


git-svn-id: http://closure-compiler.googlecode.com/svn/trunk@2460 b0f006be-c8cd-11de-a2e8-8d36a3108c74