Function constructor should avoid String.prototype methods

Replace a use of .indexOf with a call to StringIndexOf.  As always,
lexical scoping to the rescue.

R=mstarzinger@chromium.org
TEST=mjsunit/regress/regress-2686
BUG=v8:2686

Review URL: https://codereview.chromium.org/14668013

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14678 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Ignore failing flaky profiler test.

R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/14899010

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14679 ce2b1a6d-e550-0410-aec6-3dcde31c8c00